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Statement of problem: Changing the internal design of a metal framework may decrease the manufacturing time, the weight of the restoration, and the amount of alloy powder used, as well as simplify the fabrication process. Purpose: The purpose of this in vitro study was to evaluate the effect of framework internal design changes on the mechanical properties of cobalt-chromium (Co-Cr) specimens manufactured by using direct metal laser sintering (DMLS). Material and methods: Dumbbell-shaped test specimens were designed as per the International Organization for Standardization (ISO) 22674(E) standard by using a 3-dimensional software program. A total of 70 dumbbell-shaped specimens were prepared by using Co-Cr alloy powder and DMLS (n=10). The control group specimens were solid with the internal completely filled. For the test groups, the internal design of the dumbbell-shaped specimens was modified. Leaving the outer shell thickness of the specimens at 0.5 mm for all test groups, 6 different internal designs were created, and the specimens were weighed. The tensile strength test was used to evaluate the mean peak strength, elastic modulus, and percentage elongation of the specimens. One-way ANOVA followed by the Dunnett T3 test was used for statistical analysis (α=.05). Results: A statistically significant difference was found among the groups in terms of bar weight and peak strength (P.05). Conclusions: Decreasing the weight of the frameworks by changing the internal design of the specimens also decreased the peak strength. However, it did not affect the elastic modulus or the percentage of elongation.

Carbon fiber reinforced aluminum composites with ordered architectures of shear-induced aligned carbon fibers were fabricated by 3D printing. The microstructures of the printed and sintered samples and mechanical properties of the composites were investigated. Carbon fibers and aluminum powder were bonded together with resin. The spatial arrangement of the carbon fibers was fixed in the aluminum matrix by shear-induced alignment in the 3D printing process. As a result, the elongation of the composites with a parallel arrangement of aligned fibers and the impact toughness of the composites with an orthogonal arrangement were 0.82% and 0.41 ​J/cm2, respectively, about 0.4 and 0.8 times higher than that of the random arrangement.

An AZ91–0.9Ca–0.6Y–0.5 MM (AZXWMM91100) alloy, which has higher corrosion resistance, ignition resistance, and extrudability than a commercial AZ91 alloy, has been developed recently. In this study, the AZXWMM91100 alloy is extruded at various temperatures (300–400 °C) and ram speeds (1–14.5 mm/s), and the cracking behaviors, microstructure, and tensile properties of the extruded materials are systematically analyzed. On the basis of the pressure limit and surface and internal cracking limit, the extrusion limit diagram providing a safe extrusion processing zone is established. All of the materials extruded at temperatures and speeds within the safe extrusion processing zone have high surface quality and moderate tensile ductility with an elongation higher than 10%. Moreover, they have a fully recrystallized grain structure and contain undissolved particle stringers arranged parallel to the extrusion direction. The grain size of the extruded material does not show any relationship with the Zener–Hollomon parameter (Z). However, the yield strength (YS) of the extruded material is inversely proportional to the logarithm of the Z value, and their relationship is expressed as YS = −31.2•log(Z) + 536. These findings may broaden the understanding of the AZXWMM91100 alloy with excellent chemical and physical properties and provide valuable information for the development of high-performance extruded Mg products using this alloy.

Specific gravity segregation that occurs during the smelting process always leads to the low composition homogeneity and poor performance stability of the magnesium-rare earth (Mg-RE) alloys. In this study, the segregation behavior of Mg-Gd alloy was investigated by sampling from different locations in the ingot fabricated by a resistance furnace without a pouring process. The combined application of induction-heating and mechanical stirring with various speeds (0–130 r/min) was applied to promote the distribution homogeneity of Gd atoms. In the resistance-heating fabricated ingot, Gd content at the bottom section reaches 407% of that at the top. The coarse dendrites surrounded by the network-like eutectic structures are responsible for the brittle fracture with a poor elongation of 3.7%. By the combined employment of the induction heating and mechanical stirring with the speed of 87 r/min at 740 °C for 40 s, the variation of the Gd content within the whole ingot can be reduced to be the minimum of 0.23 wt%. Corresponding formation and regulating models of segregation were also proposed. However, the cooling rate of the melt is reduced by the continuous increase of the stirring speed to 130 r/min, which results in the grain coarsening and lower homogeneity of the ingot.

Statement of problem The climate of tropical Southeast Asia includes high humidity and ultraviolet radiation that reduce the lifespan of silicone prostheses by inducing changes in their mechanical properties and color stability. Studies on the surface roughness (SR) and mechanical properties of different silicone elastomers (SEs) subjected to the natural tropical weather of Southeast Asia are lacking. Purpose The purpose of this in vitro study was to evaluate the SR, tensile strength (TS), and percentage elongation (% E) of different SEs subjected to outdoor weathering in the Malaysian climate. Material and methods Type-II dumbbell-shaped specimens (N-120) (nonweathered=15, weathered=15) were made from 3 room-temperature vulcanized (A-2000, A-2006, and A-103) and 1 heat-temperature vulcanized (M-511) silicone (Factor II). For 6 months, weathered specimens were subjected to outdoor weathering inside a custom exposure rack. Simultaneously, the nonweathered specimens were kept in a dehumidifier. Subsequently, the SR was measured with a profilometer; TS and % E were measured by using a universal testing machine. Two-way ANOVA was used to compare the means of the tested properties of the nonweathered and weathered specimens, and pairwise comparison was carried out between the silicones (α=.05). Results After outdoor weathering, the SR, TS, and % E were adversely affected by weathering in the Malaysian environment. Among the silicone materials, A-2000 showed the least TS changes (2.51 MPa), while A-2006 demonstrated significant changes in percentage elongation after outdoor weathering (266.5%). M-511 exhibited the highest mean value (2.50 μm) for SR changes. In addition, A-103 SE showed statistically significant differences in most pairwise comparisons for all 3 dependent variables. Conclusions Based on the evaluation of mechanical properties, A-103 can be suggested as a suitable silicone for maxillofacial prostheses fabricated for tropical climates. However, A-2000 can be a suitable alternative, although significant changes to surface roughness were detected after outdoor weathering.

The effects of hydride amount (20–850 wppm), orientation (circumferential and radial), and temperature (room temperature, 100 °C, 200 °C) on the axial mechanical properties of Zircaloy-4 cladding were comprehensively examined. The fraction of radial hydride fraction in the cladding was quantified using PROPHET, an in-house radial hydride fraction analysis code. Uniaxial tensile tests (UTTs) were conducted at various temperatures to obtain the axial mechanical properties. Hydride orientation has a limited effect on the axial mechanical behavior of hydrided Zircaloy-4 cladding. Ultimate tensile stress (UTS) and associated uniform elongation demonstrated limited sensitivity to hydride content under UTT. Statistical uncertainty of UTS was found small, supporting the deterministic approach for the load-failure analysis of hydrided Zircaloy-4 cladding. These properties notably decrease with increasing temperature in the tested range. The dependence of yield strength on hydrogen content differed from temperature to temperature. The ductility-related parameters, such as total elongation, strain energy density (SED), and offset strain decrease with increasing hydride contents. The abrupt loss of ductility in UTT was found at ∼700 wppm. Demonstrating a strong correlation between total elongation and offset strain, SED can be used as a comprehensive measure of ductility of hydrided zirconium alloy.

For additive manufactured aluminum alloys, the inferior mechanical properties along the building direction have been a serious weakness. In this study, an optimized heat treatment was developed as a simple and effective solution. The effects of direct aging on microstructure and mechanical properties along the building direction of AlSi10Mg samples produced via selective laser melting (SLM) were investigated. The results showed that, compared with the conventional heat treatment at elevated temperatures, direct aging at temperatures of 130–190 °C could retain the fine grain microstructure of SLM samples and promote further precipitation of Si phase, however, the growth of pores occurred during direct aging. With increasing aging temperature, while finer cell structures were obtained, more and larger pores were developed, resulting in decreased density of the samples. Two types of pore formation mechanisms were identified. Considering the balance between the refinement of cell structure and the growth of pores, aging at 130 °C was determined as the optimized heat treatment for SLM AlSi10Mg samples. The tensile strength along the building direction of the 130 °C aged sample was increased from 403 MPa to 451 MPa, with relatively high elongation of 6.5%.

Regarding the as-cast Mg-9.5Gd-4Y-2.2Zn-0.5Zr alloy, the effect of heat treatment on its properties at room temperature (RT), as well as the mechanical properties and microstructure evolution of various peak-aging samples at different tensile temperatures were discussed in this article. The results indicated that the optimal heat treatment process of the alloy was: 520 °C × 24 h + 200 °C × 112 h. Under this condition, the yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) at RT were: 238 MPa, 327 MPa and 2.5 %, respectively. As the tensile temperature increases, the strength increases firstly and then decreases, but the ductility increases monotonously. The microstructures evolution of 200 °C peak-aging (200PA) and 250 °C peak-aging (250PA) samples were different with the increasing tensile tenperature. When tensile test processed at 150°C, the dense β' phase and rod-shaped basal γ' phase will be formed in the 200PA sample. However, at 300 °C, the β' phases disappeared. The β' and LPSO phases in the 250PA sample coarsened gradually as the tensile temperature increased, and 14H-LPSO phases were formed during tensile at 300 °C. The 200PA sample reached the highest strength when tensile at 150 °C, which was attributed to the hindrance of the basal dislocation and non-basal dislocation slip by the prismatic β' phases and the newly formed basal γ' precipitates.

The trade-off between strength and ductility has been an enormous difficulty in the field of materials for an extended time due to their inverse correlation. In this work, friction stir processing (FSP) was for the first time performed to high-strength and high-melting-point Ni-Co based superalloy (GH4068), and enhanced strength and ductility were achieved in FSP samples. At room temperature, the FSP sample demonstrated significantly higher yield strength and ultimate tensile strength (1290 and 1670 MPa) than that of the base material (BM, 758 and 904 MPa) and advanced wrought GH4068 alloy (982 and 1291 MPa), concurrent with high tensile ductility (∼24%). Compared with the BM, 70% higher yield strength of the FSP sample results from the remarkable contribution of grain-boundary and nanotwin strengthening, which has been confirmed by the multimechanistic model studied in this work. More importantly, with increasing temperature, an excellent strength-ductility synergy was obtained at 400 °C, i.e., the yield strength of the FSP sample was increased by more than 50% compared with the BM (from 789 to 1219 MPa); more interestingly, the elongation was also significantly increased from 17.9% in the BM to 28.5% in the FSP sample. Meanwhile, the Portevin-Le Chatelier effect was observed in the engineering stress-strain curve. The occurrence of this effect may be attributed to the interaction between solutes and defects like twins and mobile dislocations. Moreover, the grain refinement mechanism of FSP samples was proved to be discontinuous dynamic recrystallization.

In this study, the effects of annealing and solution aging heat treatment on the microstructure and mechanical properties of cold spray additive manufactured (CSAMed) AA2024/Al2O3 composite were investigated. The results showed that both annealing and solution aging enhanced the interfacial bonding between the deposited AA2024 particles in the composite. The tensile properties of CSAMed AA2024/Al2O3 composite were significantly improved by 13.8% for ultimate tensile strength and 47.8% for elongation after solution aging. Microstructural examination and fractographic analysis showed that the fracture mechanism between the adjacent AA2024 particles changed from brittle to ductile-dominant mode after heat treatment. However, the interfacial bonding between the AA2024 and Al2O3 particles cannot be improved. For the improvement of mechanical properties, the solution aging was slightly better than annealing. In addition, low-temperature annealing greatly reduced the anisotropy of the mechanical properties of CSAMed AA2024/Al2O3 composite.

Strength and ductility synergy in an Mg-3mass%Al-Mn (AM30) alloy sheet was successfully improved via twin-roll casting and annealing at low-temperature. An AM30 alloy sheet produced by twin-roll casting, homogenization, hot-rolling, and subsequent annealing at 170 °C for 64 h exhibits a good 0.2% proof stress of 170 MPa and a large elongation to failure of 33.1% along the rolling direction. The sheet also shows in-plane isotropic tensile properties, and the 0.2% proof stress and elongation to failure along the transverse direction are 176 MPa and 35.5%, respectively. Though the sheet produced by direct-chill casting also shows moderate strengths if the annealing condition is same, the direct-chill casting leads to the deteriorated elongation to failure of 23.9% and 30.0% for the rolling and transverse directions, respectively. As well as such excellent tensile properties, a high room-temperature stretch formability with an Index Erichsen value of 8.3 mm could be obtained in the twin-roll cast sheet annealed at 170 °C for 64 h. The annealing at a higher temperature further improves the stretch formability; however, this results in the decrease of the tensile properties. Microstructure characterization reveals that the excellent combination of strengths, ductility, and stretch formability in the twin-roll cast sheet annealed at the low-temperature annealing is mainly attributed to the uniform recrystallized microstructure, fine grain size, and circular distribution of (0001) poles away from the normal direction of the sheet.

Using the calculation of phase diagrams approach and Scheil solidification modeling, the Al-2.5Mg-1.0Ni-0.4Sc-0.1Zr alloy was designed, intentionally with an extraordinarily high cracking susceptibility, making it prime for solidification cracking during laser powder bed fusion. This study demonstrates the ability to mitigate even the most extreme solidification cracking tendencies in aluminum alloys with only minor alloying additions of Sc and Zr, 0.5 wt.% max. Furthermore, by employing a simple direct ageing heat treatment, good tensile mechanical properties were observed with a yield strength of 308 MPa, an ultimate tensile strength of 390 MPa, and a total elongation of 11%.

Laminated multi-layer graphene/Cu–Al–Mn composites were prepared via packaged hot roll bonding process for the first time. Microscopic observation shows that the grains in the Cu–Al–Mn layers are remarkably refined. Multi-layer graphene films intermittently disperse at the interfaces between Cu–Al–Mn layers. Some small fragments of multi-layer graphene films are squeezed into the Cu–Al–Mn layer, and around them, due to the formation of in-situ Al2O3 phase and nano-twins, multi-stage and multi-phase structures are formed. Performance tests show that the composites have ultrahigh damping capacity. Within a wide temperature range of 25–300 °C, the value of damping plateau is up to 0.1 (about 10 times that of the original Cu–Al–Mn alloy). The composites also have superior tensile mechanical properties. Their tensile strength and elongation are up to 913.3 MPa and 13.4% respectively (2.5 times and 4.1 times that of the original Cu–Al–Mn alloy). Microstructural origins of the excellent comprehensive properties were discussed in detail.

The mechanical properties of TiAl alloy prepared by directional solidification were predicted through a machine learning algorithm model. The composition, input power, and pulling speed were designated as input variables as representative factors influencing mechanical properties, and multiple linear regression analysis was conducted by collecting data obtained from the literature. In this study, the R2 value of the tensile strength prediction result was 0.7159, elongation was 0.8459, nanoindentation hardness was 0.7573, and interlamellar spacing was 0.9674. As the R2 value of the elongation obtained through the analysis was higher than the R2 value of the tensile strength, it was confirmed that the elongation had a closer relationship with the input variables (composition, input power, pulling speed) than the tensile strength. By adding the elongation to the tensile strength as an input variable, it was observed that the R2 value was further increased. The tensile test prediction results were divided into four groups: The group with the lowest residual value (predicted value-actual value) was designated as group A, and the group with the largest residual value was designated as group D. When comparing the values of group A and group D, more overpredictions occurred in group A, while more underpredictions occurred in group D. Using the residuals and R2 values, the cause of the well-prediction was studied, and through this, the relationship between the mechanical properties and the microstructure was quantitatively investigated.

Laser solid forming (LSF) technology can be used to rapidly manufacture and repair high-strength steel parts with superior performance, but the value of the heat input during operation is difficult to quantify, which has a substantial impact on the microstructure and mechanical properties of the parts. A promising method to improve the forming efficiency and quality of LSFed parts is to accurately control the heat input and explore its relationship with the microstructure and mechanical properties. To remove the interference of other variables from the experiment, the dimensionless heat input Q* was introduced. The Q* values were designed in advance to calculate the experimental parameters used to perform the LSF experiment. The microstructure was observed at different regions of the sample, and its mechanical properties were analyzed. From the results, the following conclusions were drawn. The Q* value was directly related to the cooling rate and heat accumulation in the top structure, leading to the formation of different microstructures; it also modified the original structure at the bottom, affecting the subsequent thermal cycle and indirectly changing the tempered martensite morphology. The heat input also affected the mechanical properties of the sample. The hardness of the stable zone decreased with increasing Q* value, and the lowest value was 190 HV. Similarly, the tensile strength and yield strength of the LSFed samples decreased considerably with increasing Q* value, and the lowest values were 735 and 604 MPa, respectively. Only the elongation and reduction in the area increased after a slight decrease. The Q* value had a significant effect on heat treatment. When Q* = 2.9, the increase in tensile strength and yield strength after heat treatment was the largest (29% and 44%, respectively).

Nanocrystalline metals often display a high strength up to the gigapascal level, yet they suffer from poor plasticity. Previous studies have shown that the development of hetero-sized grains can efficiently overcome the strength-ductility trade-off of nanocrystalline metals. However, whether this strategy can lead to the fabrication of nanocrystalline nanowires exhibiting both high strength and superplasticity is unclear, similar to the atomistic deformation mechanism. In this paper, we show that ultra-small nanocrystalline Au nanowires comprising grains in both the Hall–Petch and inverse Hall–Petch grain-size regions can exhibit extremely high uniform elongation (236%) and high strength (2.34 gigapascals) at room temperature. In situ atomic-scale observations revealed that the plastic deformation underwent two stages. In the first stage, the super-elongation ability originated from the intergrain plasticity of small grains via mechanisms such as grain boundary migration and grain rotation. This intergrain plasticity caused the grains in the heterogeneous-structured nanowires to grow very large. In the second stage, the super-elongation ability originated from intragrain plasticity accompanied by the diffusion of surface atoms. Our results show that the hetero-grain-sized nanocrystalline nanowires, comprising grains with sizes both in the strongest Hall–Petch effect region and the inverse Hall–Petch effect region, were simultaneously ultra-strong and ductile. They displayed neither a strength-ductility trade-off nor plastic instability.

The effect of specimen thickness on the rupture properties of cast Ni-based polycrystal superalloy M951 was investigated in this paper. The results of the rupture tests in air under 980 ​°C/90 ​MPa revealed that the rupture life and elongation obviously decreased with decreasing specimen thickness. The thin-wall effect for polycrystal superalloy M951 is associated with several factors. First, the surface oxidation and internal nitridation induce the reduction in the load-bearing section, which accelerates the rupture fracture of thin specimens. Second, the combined effect of oxidation and stress at the surface grain boundary facilitates the premature initiation and propagation of the surface cracks in thin specimen. Third, the through-grain boundaries introduce by specimens machining are detrimental for rupture property. A direct comparison of rupture properties of thin-wall samples with different grain morphologies indicate that thin-wall effect can be diminished by avoiding through-grain boundary introduction.

In the present study, the micro-mechanical behavior of CoCrFeMnNi high-entropy alloy was investigated using an in-house micro-tensile setup at room temperature and 550 °C at different strain rates. Micro-mechanical properties are compared with those obtained using a commercial macro-tensile setup to check a potential sample size effect. Results show that mechanical properties such as yield strength, ultimate tensile strength and uniform elongation are independent of the sample size. However, the total elongation-to-failure of micro-samples is found to be lower than those of macro-counterparts. Apart from this, the material exhibits serrated plastic flow, which is strain rate dependent in terms of the onset strain and shape of serrations at 550 °C. Furthermore, transmission electron microscopy investigations were performed to correlate the occurrence of serrations to the observed distinct dislocation structures. Microstructural results provide direct evidence that dislocations are curved and hence effectively pinned and unpinned at the lowest applied strain rate, which might be responsible for the occurrence of serrated plastic flow.

Combined with the topology optimization, additive manufacturing can be used to fabricate metal parts with complex shapes. However, due to the geometrical variations and microstructure heterogeneities of the additively manufactured metal parts, new standards with the use of miniature specimens are required for the evalutation of the spatial distribution of mechanical properties throughout the parts. Here, we conduct a systematic investigation on tensile and fatigue properties of selective laser melted Inconel 718 specimens with different thicknesses ranging from 0.1 mm to 1 mm. A “microstructure unit” that can well reflect the microstructure characteristic of selective laser melted materials is defined. The results reveal that premature necking with a dramatic drop in uniform elongation occurs if the ratio (t/d) of specimen thickness (t) to the "microstructure unit" size (d) is less than one. Premature necking is mainly attributed to the transition of strain localization behavior. We also propose a probabilistic statistical model for fatigue limit prediction based on the available fatigue data. It is recommended that the criterion of t/d ≥ 4 should be satisfied to ensure that the yield strength, the uniform elongation, and the fatigue limit determined by the miniature specimens are comparable with those determined by standard specimens. The findings may provdie a guide to the establishment of miniature specimen-based standards toward the qualification of additively manufactured metal parts.

Although having suitable mechanical properties, the high corrosion and resorption rate of biocompatible Mg alloys make them unsuitable for implant applications. Reducing the corrosion rate of the alloys by altering the metallurgical properties can be potentially beneficial for such applications. Friction stir processing (FSP) is an established process to induce changes in the surface microstructure of metals, and in this study, this process has been explored as a potential method to modify the metallurgical microstructure of the alloy. There is an increase of 13 % of microhardness and there is a 21 % reduction in ultimate stress in exchange of 15 % increase in % elongation in friction stir processed AZ31 magnesium alloy. The results indicate that the induced changes in the metallurgical microstructure by FSP process can augment the resistance to corrosion without significantly deteriorating the mechanical properties as observed from tests conducted in a simulated biological environment. Further experimentation is required to optimize the processing condition and establish the relationship between the evolved metallurgical microstructures and the mechanical and electrochemical properties.

The property evaluation of Aluminum alloys a quite a challenging task and is an essential one to achieve improved mechanical and metallurgical properties during casting. This paves the way for the present research, in which the casting of commercial A356 and A319 Al alloys have been performed under stationary and vibratory state. The vibrational recurrence has been varied between 0 Hz and 400 Hz with a constant amplitude of 15 μm during casting. Thereafter, the quality of both casted materials has been evaluated by measuring their yield strength, ultimate tensile strength and % elongation. Experimental results revealed that the higher intensity of oscillation improves mechanical properties with the reduced grain size of α-Al. It has been also observed that the fraction of nucleation sites is increased due to the vibration.

Ultrafast heating (UFH) at the rates of 10–300 °C/s was employed as a new strategy to anneal a cold-rolled 7wt% Mn steel, followed by the immediate cooling. Severely deformed strain-induced martensite and lightly-deformed thermal martensite, both had been already enriched with C and Mn before, transformed to fine and coarse austenite grains during the UFH, leading to the bimodal size distribution. Compared with the long intercritical annealing (IA) process, the UFH processes produced larger fraction of RA grains (up to 37%) with a high density of dislocation, leading to the significant increase in yield strength by 270 MPa and the product of strength and elongation up to 55 GPa% due to the enormous work hardening capacity. Such a significant strengthening is first attributed to high density dislocations preserved after UFH and then to the microstructural refinement and the precipitation strengthening; whilst the sustainable work hardening is attributed to the successive TRIP effect during deformation, resulting from the large fraction of RA instantly formed with the bimodal size distribution during UFH. Moreover, the results on the microstructural characterization, thermodynamics calculation on the reverse transformation temperature and the kinetic simulations on the reverse transformation all suggest that the austenitization during UFH is displacive and involves the diffusion and partition of C. Therefore, we propose that it is a bainite-like transformation.

Journal of magnesium and alloys 10(1), 146-159 (2022). doi:10.1016/j.jma.2021.07.003, Published by Elsevier, Amsterdam [u.a.]

The microstructure, phase composition, texture, and tensile properties of Ti48Al2Cr2Nb5Ta alloy prepared by laser additive manufacturing (LAM) were all investigated in detail. The microstructure of the alloy is constituted of α2(Ti3Al), γ(TiAl), and β/B2 (β ordered to B2) phases, according to the results. The microstructure changes from lamellar structure to lamellar structure divided by massive β/B2 phase when the laser power increases from 1.0 kW to 2.2 kW. Furthermore, when the laser power is 2.2 kW, the content of the β/B2 phase achieves its highest value (9.43%), whereas when the laser power is 1.8 kW, the content of the α2 phase reaches its maximum value (9.43%). The crystal texture of the γ(111) and α2(0001) orientations strengthens as laser power increases. Tensile characteristics demonstrate that the 1.4 kW alloy has the best tensile strength and elongation at room temperature and 750 °C, with values of 677 MPa, 651 MPa, and 1.8%, 2.2%, respectively. However, when compared to other alloys, the 1.4 kW alloy's tensile strength and elongation at 850 °C are slightly lower (538 MPa 13%).

In this work, biocomposites based polylactic acid (PLA) filled with piper betle fiber (PBF) were successfully synthesized by solvent cast-film method using chloroform as the solvent. The PBF was treated with 7% NaOH. The biocomposites were loaded separately with untreated and treated PBF at 1 to 3 wt% and investigated for tensile properties and morphological of fractured surfaces. Tensile strength and modulus elasticity of biocomposites were increased with addition of betel particles and found to be higher than the matrix. Furthermore, the alkali treatment of PBF had considerably improved tensile and modulus of biocomposites compared to those of biocomposites with untreated PBF. A contrary trend was found in the case of elongation at break. However, biocomposites with treated PBF had greater elongation compared to those of biocomposites with untreated PBF. These results were identified by fracture examination with scanning electron microscopy (SEM). SEM observations showed the good bonds formed between treated PBF and PLA. This indicated by less cavity and roughness on biocomposite fractured surface with treated PBF.

The present study highlights the influences of input process variables on the elongation property of nylon 6 thermoplastic prototypes prepared by the fused filament fabrication (FFF) process. In this study, the FFF process has been conducted by varying the input process variables such as; infill percentage (70, 85 and 100%), bed temperature (50, 60 and 70 °C) and outer perimeters (4, 5 and 6 perimeters). The parts of nylon 6 thermoplastic have been prepared as per the dimension of ASTM D 638 type IV. The prepared parts have been subjected to universal tensile testing (UTT) for the investigations of elongation as the outcome of varying input process parameters. The elongation properties have been optimized by conducting the analysis based upon the signal to noise (SN) ratio of the elongation property.

PURPOSE To evaluate the effect of suture augmentation (SA) of 7-mm and 9-mm diameter graft on load sharing, elongation, stiffness, and load to failure for all-inside anterior cruciate ligament reconstruction (ACLR) in a biomechanical Study was funded by Arthrex ID: EMEA-16020. full-construct porcine model. METHODS Bovine tendon grafts, 7-mm and 9-mm diameter, with and without SA were tested using suspensory fixation (n = 8). The independent SA was looped over a femoral button and knotted on a tibial button. Preconditioned constructs were incrementally increased loaded (100N/1,000 cycles) from 100N to 400N for 4,000 cycles (0.75 Hz) with final pull to failure (50 mm/min). Isolated mechanical and optical measurements during construct loading of the SA allowed to quantify the load and elongation range during load sharing. Construct elongation, stiffness and ultimate strength were further assessed. RESULTS Load sharing in 7-mm grafts started earlier (200N) with a significant greater content than 9-mm grafts (300N) to transfer 31% (125N) and 20% (80N) of the final load (400N) over the SA. Peak load sharing with SA reduced total elongation for 7-mm (1.90 ± 0.27 mm vs 4.77 ± 1.08 mm, P < .001) and 9-mm grafts (1.50 ± 0.33 mm vs 3.57 ± 0.54 mm, P < .001) and adequately increased stiffness of 7-mm (113.4 ± 9.3 N/mm vs 195.9 ± 9.8 N/mm, P < .001) to the level of augmented 9-mm grafts (208.9 ± 13.7N/mm). Augmentation of 7-mm (835 ± 92N vs 1,435 ± 228N, P < .001) and 9-mm grafts (1,044 ± 49N vs 1,806 ± 157N, P < .001) significantly increased failure loads. CONCLUSIONS Load sharing with SA occurred earlier (200N vs 300N) in lower stiffness 7-mm grafts to carry 31% (7-mm) and 20% (9-mm) of the final load (400N). Loads until peak load sharing were transferred over the graft. Augmented constructs showed significantly lower construct elongation and increased stiffness without significance between variable grafts. Failure load of augmented grafts were significantly increased. CLINICAL RELEVANCE Suture tape ligament augmentation may potentially protect biological grafts from excessive peak loading and elongation, thus reducing the risk of graft tears.

Tailor Welded Blanks (TWBs) are now-a-days being used in many vehicles due to its advantage of reduced vehicle weight. In the decades from year 1990 to 2010, TWBs manufactured of high-strength steel alloys were the focus of the researchers' research. After year 2010 onwards, the focus of automotive industry shifted towards use of aluminum alloys and resulted in more research work related to welding process of aluminum alloys. In this research work, Friction Stir Welding (FSW) is used to join aluminum alloys AA6061-T6 and AA5052-H32. Process parameters of FSW i.e. Spindle Speed (N), Shoulder Dia. (SD) and Feed (f) are optimized by Response Surface Method (RSM) approach. Output parameters like Ultimate Yield Strength (UTS) and % Elongation are considered. Multi-objective optimization by RSM approach suggests that shoulder diameter = 16 mm, spindle speed = 1500 rpm and feed = 40 mm/min are optimum results obtained and when kept at this level will provide UTS in the range of 160 MPa-180 MPa and 10 % to 11 % elongation can be expected for friction-stir-welded blanks.

This research work highlights the influence of fused deposition modeling (FDM) process parameters on the selected mechanical properties such as young’s modulus and surface roughness of FDM prints have been studied by using Taguchi designed L9 orthogonal array (OA) design of experiments (DOEs). Polylactic acid (PLA) feedstock filament has been used for the fabrication of specimens (as per ASTM D638 standard). The critical input parameters selected were namely layer thickness, raster angle and infill pattern. The strength at peak varies in the range of 26 to 38.91 (MPa), whereas strength at break lies in the range of 23.4 to 35.02 (MPa). Elongation at peak lies in the range of 5%-6%. Surface roughness along X axis lies in the range of 3.18 µm to 9.21 µm, whereas along Y axis, it remains in the range of 3.133 µm to 9.512 µm. The average value lies in the range of 4.44 µm to 7.18 µm. The results show that the specimen prepared with the combination of layer thickness 0.16 mm, raster angle 60° and cubic infill pattern has very good mechanical properties.

A dramatic improvement of strength and ductility of cast Al-2.5Li-1.5Cu-1Zn-0.5Mg-0.15 Zr alloy was obtained by the collaboration of Sc-alloying and optimized ageing scheme. Joint and independent influence of Sc-alloying and different ageing temperatures were investigated. The results revealed that a substantial increase was realized in the hardness of Sc-containing alloy, and the ageing response time was only influenced by ageing temperature. Coarse and heterogeneous δ' (Al3Li), wide δ'-precipitation free zones (δ'-PFZs), and a large amount of T1 (Al2CuLi) precipitates were observed in Sc-containing alloy aged at 175 °C, which resulted in superior yield strength and poor elongation. The Sc-containing alloy obtained an excellent combination of ductility (elongation = 8.2 %) and tensile strength (ultimate strength =565 MPa) suffered to 150 °C ageing for 64 h. The increase in the elongation was mainly due to the combined effect of grain refining, much finer δ', and extremely narrow δ'-PFZs (

The hydrophobicity of natural rubber (NR) film provides it with a potential material for preparation of controlled drug delivery systems. The purpose of this study was to develop the NR/gelatin composite capsule shells for controlled drug release. The NR film and the NR/gelatin composite films, at the NR: gelatin ratio of 3:7, 4:6, 5:5, 6:4 and 7:3, were prepared. It was found that the composite films possessed higher strength and modulus, but lower elongation than the NR film. The smooth NR film absorbed water/aqueous media only to a small extent and hence scarcely eroded. Incorporation of gelatin resulted in the rough films, which were capable of absorbing more water/aqueous media and, therefore, eroding more than the NR film. The capsule shells were subsequently prepared from the NR: gelatin ratio of 6:4 composite film, contributing to its good mechanical properties and minimal erosion. Propranolol HCl was filled into the developed capsule shells. The drug was gradually released and reached the maxima within 8 and 4 h, in pH 1.2 and 6.8 buffer solutions, respectively. Thus, the NR/gelatin composite capsule shells were successfully prepared and able to control the drug release efficiently.

In order to obtain a uniform and effectively toughened poly (lactic acid) film by blending with low content of poly (ethylene octene) (POE) with high elasticity, the tailored interfacial intermolecular interaction and entanglement between the two phases of the PLA/POE blend was innovatively constructed via the facile reactive melt blending process through the reaction of the epoxy/anhydride groups grafted on the POE chains with the end groups of PLA chains (PLA/GPOE-MPOE). It was observed that POE domains were embedded tightly in PLA matrix with a fuzzy interface and abundant interface transition area, and the impact fractured surface of the blend showed an obvious plastic deformation with less occurrence of fibrillation of PLA matrix or interfacial de-bonding. Compared with neat PLA and directly blended PLA/POE blends, the PLA/GPOE-MPOE blend exhibited much higher complex viscosity/storage modulus, much lower tanδ values in the terminal region, and obvious strain-hardening behavior. The deviation in viscoelastic behavior of PLA/GPOE-MPOE from linear PLA indicated the enhanced molecular entanglement between the long-branched chains, resulting in an enhancement of the stretching ability during biaxial drawing of the blend. Uniform PLA/GPOE-MPOE films with draw ratio as high as 7 × 7 were obtained through biaxial stretching, which showed much higher tensile strength and the elongation at break than that of neat PLA and PLA/POE film. This work provides a facile method for fabricating toughening PLA films with application potentials.

A recyclable thermoplastic polyurethane (TPU)/Silicone thermoplastic vulcanizate (TPV) consisting of TPU, Silicone, and additives (i.e. crosslinking agent, antioxidant, compatilizers, and processing aid) with high tensile strength (10.0 MPa), good elongation (322%), low abrasion rate (0.11%), proper hardness (Shore A83), and low static/kinetic friction coefficient (0.72/0.61) has been successfully manufactured. Moreover, we have also prepared the prototype for bands of smart bracelets based on lab-made TPU/Silicone TPV, demonstrating that it is a highly potential recyclable material for wearable devices.

Increasing the toughness of poly(lactic acid) (PLA), i.e., simultaneously increasing both the tensile strength and ductility, remains a major challenge. In this study, fully bio-based PLA blends with polydecalactone (PDL)-grafted cellulose copolymer (CgPD) were prepared and comprehensively analyzed to enhance the toughness of the PLA matrix. The blends were found by FT-IR and solid-state 1H NMR to be physically intact and miscible at the sub-twenty-nanometer scale. The WXRD and DSC analyses indicated that the addition of the alkyl-branched CgPD imparts a more structurally disordered PLA mesophase state to the prepared PLA_CgPD bio-blends. UTM analysis was used to characterize the macroscopic mechanical properties of the PLA_CgPD bio-blends. Both the tensile strength and elongation properties were simultaneously improved with the addition of 1 wt% CgPD loading amount to PLA (PLA_CgPD1). This study experimentally demonstrates that the enhanced mechanical properties of PLA_CgPD1 are closely related to the existence of more ordered PLA mesophases induced by the introduction of an optimal amount of CgPD into the PLA matrix.

In this paper, a novel Cu-1.5Ni-1.1Co-0.6Si-0.1Cr (wt.%) alloy with high strength and electrical conductivity was designed. After aging, excellent properties of 857±12 MPa yield strength, 300±8 HV microhardness, 42.8 ± 2.5% IACS conductivity, and 7 ± 0.5% elongation were obtained. According to the atomic structure, part of Ni atoms in Ni2Si can be replaced by Co atoms to form nano-precipitates (Ni, Co)2Si. The alloy's high strength and conductivity are mainly attributed to the fine and uniformly distributed (Ni, Co)2Si and Cr nano precipitates. The alloy strength was also enhanced by twins, dislocations, and grain refining strengthening. Based on the investigations of deformation microstructure and the orientation relationship between the (Ni, Co)2Si precipitates and the Cu matrix, the main reason for elongation increase is attributed to the formation of deformation twins and the small lattice mismatch strain at the coherent interfaces of precipitates and the Cu matrix.

Cu content has been successfully optimized in a thixo-cast and directly aged (T5-treatment) Al–7Si–0.5Mg (wt.%) alloy. Even after the 0.5% Cu addition, plate-like Al2Cu (θ’) phases, which contribute to high strengths and large plasticity, are precipitated. The formation of a large fraction of Cu-containing brittle phases could be suppressed as well. Then, the Al–7Si–0.5Mg–0.5Cu alloy exhibits high ultimate tensile strength, 0.2% proof stress, and elongation to failure of 296 MPa, 209 MPa, and 8.8%, respectively. This results in a high quality index similar to that of solution-treated and subsequently aged (T6-treated) Al–7Si–Mg alloys. A Cu addition over 1.0% further improves the strengths; however, this leads to poor ductility because of the high fraction of Cu-containing brittle phases.

Seed germination and coleoptile elongation in response to flooding stress is an important trait for the direct seeding of rice. However, the genes regulating this process and the underlying mechanisms are little understood. In this study, bZIP72 was identified as a positive regulator of seed germination under submergence. Transcription of bZIP72 was submergence induced. Over-expression of bZIP72 enhanced submerged seed germination and coleoptile elongation, while bzip72 mutants exhibited the opposite tendency. Using biochemical interaction assays, we showed that bZIP72 directly binds to the promoter of alcohol dehydrogenase 1 (ADH1), enhances its activity, and subsequently produces more NAD+, NADH and ATP involved in the alcoholic fermentation and glycolysis pathway, ultimately providing necessary energy reserves thus conferring tolerance to submergence. In summary, this research provides novel insights into bZIP72 participation in submerged rice seed germination and coleoptile elongation.

In the present work, thermal exposure was performed on the 7B50-T7451 aluminium alloy friction stir welding (FSW) joints at different temperatures (150 °C, 175 °C and 220 °C) for 200h. The results show that the microstructure and mechanical properties of as-welded joints along the thickness direction of the plate are heterogeneous. The hardness and strength of FSW joints decrease while the elongation continuously increases with increasing thermal exposure temperature. Compared with the base material, the joints present much higher hardening capacity which is further increased with increasing temperature. The precipitates in the heat-affected zone (HAZ) exhibit continuous coarsening and the precipitate distribution becomes broader as the temperature rises. The transformation from η' phase to η phase is obvious at 220 °C. The weld nugget zone (WNZ) re-precipitates a large number of nano-scale η particles subjected to 200h thermal exposure at 150 °C and re-precipitated η phase in WNZ of the double-sided joint has reached micron-sized at 175 °C and 220 °C. When exposed at different temperatures, all FSW joints show typical ductile fracture features. Fracture positions at different thermal exposure temperatures are inconsistent and this variation is closely related to different microstructural characteristics.

The demand for magnesium (Mg) alloy with high elongation, certain strength and good degradation rate used in oil and gas exploitation filed is increasing. Based on Mg-2Gd alloy, effect of copper (Cu) addition (0.25, 0.5 and 0.75 wt.%) on microstructure, mechanical properties and degradation rate were investigated. It showed that more Mg2Cu second phases were precipitated and the grain size was refined with increasing Cu content, accompanied with texture changing from 11 2 ¯ 1 > //ED to 01 1 ¯ 0 > //ED. As a result, hardness, tensile strength, compressive strength and degradation rate were enhanced while the strain hardening rate and elongation decreased. Nevertheless, the elongation was still up to at least 20%. Overall, the comprehensive mechanical properties and degradation rate of Mg-2Gd alloy can be effectively coordinated by Cu addition.

In this study, SiCp/AZ91 composites with enhanced mechanical properties was successfully obtained by a combined process route of equal channel angular pressing (ECAP) and rolling. The effect of ECAP and rolling on the microstructure and mechanical properties of SiCp/AZ91 composites were investigated by comparative analysis. Results showed that the high-pass ECAP process effectively refined the matrix grains and dispersed the SiCp, which gave rise to the final formation of homogenous microstructure in the rolled plate. A non-basal texture with high Schmidt factors was formed by ECAP process, while after rolling it turned into basal texture with relatively lower Schmidt factors. The SiCp/AZ91 composite obtained by the combined process method exhibited superior mechanical properties (yield strength of ∼348 MPa, ultimate strength of ∼411 MPa) and improved ductility (elongation of ∼6.3%) than the composite singly processed by rolling. The enhanced mechanical properties should be contributed to the homogenized microstructure with refined grains, uniformly distributed SiCp, accumulated dislocations and transferred texture.

In this research work, the new AA6111 matrix composites reinforced by the cooperation of nano ZrB2 particles and Gd had been designed and fabricated via in situ reaction. The addition of Gd made the nano ZrB2 particles uniformly dispersed due to the reduction of solid-particle interfacial energy (σsp) by keeping the low-energy orientation relationship. Meanwhile, it promotes the formation of equiaxed grains whose formation is also based on the nano-sized reinforcing phases as the hindering of dendrite coherency points are related to the growth restriction factor (GRF) and as the pinning effect to the grain boundaries. The fluidity was improved because of uniform viscosity and dendrites avoided meeting with the neighboring ones by the entrapment of nano-sized reinforcing phases like AlGd and ZrB2. The results indicated that AA6111–0.5 wt. % Gd-2 vol. % ZrB2 composites possessed the longest fluidity length of 70 mm. Meanwhile, the composites displayed increases of 32.7 %, 47.3 % and 52.8 % in YS, UTS and elongation, respectively, compared to the matrix alloy. A notable lattice distortion of the matrix near the ZrB2 particles and AlGd phases was proclaimed via Geometric Phase Analysis (GPA) analysis. Strengthening mechanism comprehending yield strength, containing Orowan strengthening, grain refinement strengthening, was integrally elaborated.

The intrinsic mechanical and interfacial characteristics of precipitates in Mg–Sn–Y alloys were calculated to predict strengthening precipitates and to design novel Mg alloys. The first-principle calculations results indicated that the Sn3Y5 phase had a higher bulk and shear moduli than the Mg24Y5 and Mg2Sn phases. The Mg/Sn3Y5 interface was more stable and possessed a higher adhesive strength than the Mg/Mg2Sn and Mg/Mg24Y5 interfaces. Four as-cast alloys (S10Y3 (Mg-0.5Sn-0.16Y), S5Y3 (Mg-0.43Sn-0.25Y), S1Y1 (Mg-0.36Sn-0.37Y) and S3Y5 (Mg-0.27Sn-0.48Y) alloy (at.%)) were then designed according to the different Sn to Y atomic ratios (10:3, 5:3, 1:1 and 3:5). The lower Sn to Y atomic ratio promoted the formation of the Sn3Y5 phase in the S3Y5 alloy, whereas the S10Y3 alloy with a higher Sn to Y atomic ratio mainly consisted of the Mg2Sn phase. Compared with the S10Y3 alloy, the yield strength and ultimate tensile strength of the S3Y5 alloy were increased by 70% and 16% without sacrificing the elongation at room temperature, which was greatly improved by 127% and 104% at elevated temperatures simultaneously. These results suggested that the calculations of intrinsic mechanical and interfacial characteristics of precipitates may provide an effective tool to design high-strength Mg alloys.

A novel biodegradable metal system, ZnLiCa ternary alloys, were systematically investigated both in vitro and in vivo. The ultimate tensile strength (UTS) of Zn0.8Li0.1Ca alloy reached 567.60 ± 9.56 MPa, which is comparable to pure Ti, one of the most common material used in orthopedics. The elongation of Zn0.8Li0.1Ca is 27.82 ± 18.35%, which is the highest among the ZnLiCa alloys. The in vitro degradation rate of Zn0.8Li0.1Ca alloy in simulated body fluid (SBF) showed significant acceleration than that of pure Zn. CCK-8 tests and hemocompatibility tests manifested that ZnLiCa alloys exhibit good biocompatibility. Real-time PCR showed that Zn0.8Li0.1Ca alloy successfully stimulated the expressions of osteogenesis-related genes (ALP, COL-1, OCN and Runx-2), especially the OCN. An in vivo implantation was conducted in the radius of New Zealand rabbits for 24 weeks, aiming to treat the bone defects. The Micro-CT and histological evaluations proved that the regeneration of bone defect was faster within the Zn0.8Li0.1Ca alloy scaffold than the pure Ti scaffold. Zn0.8Li0.1Ca alloy showed great potential to be applied in orthopedics, especially in the load-bearing sites., Graphical abstract Image 1, Highlights • The first research work of ZnLiCa alloys to be used as biodegradable metals. • The ultimate tensile strength (UTS) of Zn0.8Li0.1Ca alloy reached 567.60 ± 9.56 MPa, which is comparable to pure Ti, one of the most common material used in orthopedics. • Porous scaffolds made of Zn0.8Li0.1Ca showed superior bone-defect-treating effects to pure Ti scaffolds in New Zealand rabbits.

In this paper, high-strength ultrafine-grained (UFG) pure aluminum (Al) was successfully achieved via a two-step processing route including room-temperature ECAP process for continuously 16 passes and post liquid nitrogen cryo-rolling for 50% reduction. The two-step processing route was observed to produce ultrafine grains with an average grain size of 0.98 μm and has obvious advantages for the preparation of high-strength pure Al in terms of the strength-ductility synergistic effect, which endows the pure Al excellent UTS value of 180 MPa, good Ef of 17.7% and a very high increase ratio (about 84%) of strength. The high strength was mainly attributed to the outstanding fine-grain strengthening provided by the combination of large-pass ECAP and cryo-rolling. In addition, the better uniform elongation of ECAP-rolled pure Al than ECAPed one was primarily dictated by the enhanced strain hardening capacity and the elongated grain shape.

In K4750 alloy, the evolution of grain boundary (GB) precipitates, including the degradation of blocky MC carbide particles and the precipitation of granular/needle-like η phase particles, were observed after long-term aging (LA) at 750°C for 8000 h. During MC degradation, the Ti and C released from the MC carbide combined with Ni and Cr, respectively, in the γ matrix to form η-Ni3Ti phase and Cr-rich M23C6 carbide. Large amounts of granular η phase precipitated at GBs and the needle-like η phase grew gradually from GBs toward the grain interior. Because of the growth of the η phase through absorbing γ′ phase, γ′-depleted zones were formed around the η phase. The evolution of the MC carbide and η phase was primarily responsible for the decrease of the stress rupture life and the increase of elongation. After an LA sample was tested at 750°C and 360 MPa, the residual strain distribution was investigated by electron backscatter diffraction (EBSD). The results showed that the residual strain mainly distributed at GBs, especially in the region of MC degradation and at the edges of η phases, which was closely related to the appearance of phase interfaces. Microvoids/cracks easily initiated at phase interfaces, then easily extended along the γ′-depleted zones, thus the stress rupture life of LA samples was substantially shorter than that of samples subjected to the standard treatment. In particular, because of large amounts of fine degraded MC, granular M23C6 and granular η phase particles distributed at GBs after 750°C /8000 h LA and microvoid/crack formation could be hindered by the formation of dimples, which led to an increase of elongation.

We reported the influence of super-gravity field on spatial distribution of eutectic structure in Al-14.5Si alloys. The Al-14.5Si alloys were solidified under normal gravity (1 g) and various super-gravity fields (1000 g, 2000 g, 3000 g, 4000 g and 5000 g, g = 9.8 m/s2), respectively. The results indicated that the homogeneous distribution of eutectic Si could be observed in the core region of the samples solidified under super-gravity field. As the coefficient of gravity increased, the eutectic Si was significantly refined, resulting in the significant enhancement of the mechanical properties. Noted that several iron-rich phases could be observed in the core region under higher super-gravity coefficient. With the formation of the iron-rich phase, the elongation of the alloy decreased slightly. The refinement mechanism of the eutectic structure and the formation mechanism of the iron-rich phase under super-gravity field were discussed in detail.

This work aims to evaluate the use of miniaturized tensile specimen (MTS) to characterise the mechanical properties of alloys developed through rapid alloy prototyping (RAP), where high throughput tests are required on relatively small amounts of material. Tensile tests were conducted at a variety of strain rates and with increasingly smaller specimen sizes, ranging from larger specimens conforming to ASTM/ISO standards, down to small non-standard specimens. The gauge lengths of the specimens ranged from 50 to 80 mm for the standard specimens down to 5–10 mm for the non-standard specimens. To generalize the non-standard MTS designs, three alloys, DP800, DP600 and 316L stainless steel, were adopted. The results obtained from non-standard designs were compared with those from standard designs. The results show that non-standard designs can give repeatable results for yield strength (YS), ultimate tensile strength (UTS) and uniform elongation (eU). The maximum result differences of YS, UTS and eU are 7.37%, 7.71% and 11.9%, respectively, for DP alloys comparing standard and non-standard dimensions. These values are 13.56%, 14.03% and 19.5%, respectively 316L steel. The total elongation (ef) increases as the specimen dimension decreases. The geometrically dependent constants (n) are 0.2, 0.31 and 0.11 for DP800, DP600 and 316L, respectively. However, the Young's modulus is hard to determine precisely from the miniaturized designs. The conclusion from this work is that miniaturized tensile testing can be used with confidence as a high throughput means of predicting standard mechanical properties across a range of steels.

Shear assisted processing and extrusion (ShAPE) was used to extrude aluminum alloy 7075 tubing at speeds up to 12.2 m/min without surface tearing. This work presents the first experimental evidence for high-speed extrusion of 7075, which improves upon conventional extrusion where 2.0 m/min is the limit. The increased speed is primarily attributed to more extensive shear deformation, compared to conventional extrusion, which results in a high density of low angle grain boundaries that facilitate continued deformation and delay the onset of surface tearing. Mechanical testing after heat treating to the T6 condition provided an ultimate tensile strength of 565.3 ± 4.6 MPa, yield strength of 495.7 ± 8.7 MPa, and elongation of 16.4 ± 1.0%. Strength values exceed the ASTM International minimum standard and are on par with American Society for Metals (ASM) typical values, while elongation was substantially improved compared to 7 and 11% for the ASTM and ASM values respectively. It was observed that low temperature extrusion at 341 °C and 40 rpm gave superior material properties in the T6 condition compared to high temperature extrusion at 441 °C and 120 rpm because of variances in nanoscale second phase size and distribution.

Drought is a prevalent natural factor limiting crop production in arid regions across the world. To overcome this limitation, seeds are sown much deeper to boost germination by soil moisture produced by underground water. Seed pretreatment can effectively induce deep-sowing tolerance in plants. In the present study, we evaluated whether H2O2 pretreatment of seeds can initiate metabolic changes and lead to improved deep-sowing tolerance in wheat. Pretreatment with 0.05 mu M H2O2 promoted first internode elongation by 13% in the deep-sowing tolerant wheat cultivar Tir and by 32% in the sensitive cultivar Kirac-66 under deep-sowing conditions, whereas internode elongation was inhibited by diphenyleneiodonium chloride. In contrast to Tir seedlings, H2O2 levels in the first internode of Kirac-66 seedlings increased under deep-sowing condition in the H2O2-treated group compared to controls. Moreover, these seedlings had significantly lower catalase (CAT), peroxidase (POX), and ascorbate peroxidase (APX) activities but higher NADPH oxidase (NOX) and superoxide dismutase (SOD) activities under the same conditions, which consequently induced greater H2O2 accumulation. Contrary to Tir, both total glutathione and glutathione S-transferase (GST) activity decreased in Kirac-66 after deep-sowing at 10 cm. However, H2O2 treatment increased the total glutathione amounts and the activities of glutathione-related enzymes (except GST and GPX) in the first internode of Kirac-66. Taken together, these data support that H2O2 acts as a signaling molecule in the activation of antioxidant enzymes (specifically NOX, SOD, and CAT), regulation of both glutathione-related enzymes and total glutathione content, and upregulation of the cell wall-loosening protein gene TaEXPB23., Scientific and Technological Research Council of Turkey (TUBITAK) [114Z034]; Ege University Research Foundation [13-FEN-049], This work was financially supported by The Scientific and Technological Research Council of Turkey (TUBITAK), [Project No 114Z034] and the Ege University Research Foundation, [Project No 13-FEN-049].