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In-situ core-shell structured particle Ti@(Al–Si–Ti) p reinforced A356 Al alloy matrix composites were prepared by powder-thixoforming at different partial remelting temperatures, and then were solid solution treated at 545 °C for 1 h. The results indicate that the reaction between Ti cores and Al matrix operates to form nano τ 2 particles during solutionization, while the original (Al, Si) 3 Ti phases transform into τ 2 phases, and simultaneously, the early-formed nano τ 2 particles grow into large-sized plates. These behaviors are enhanced with rising the remelting temperature. The content of eutectic Si and solubility of Si in α-Al phase in the solutionized composites further decrease with rising remelting temperature, due to the reaction and phase transformation, and de-dissolution of Si, respectively. The tensile properties of the solutionized composites first increase and then decrease as the temperature rises, and the composite thixoformed at 595 °C has the highest comprehensive mechanical properties, an ultimate tensile strength of 267.0 MPa, yield strength of 178.6 MPa and elongation of 21.0 %, increased by 3.1 %, 13.3 % and 15.4 % compared with those of the as-fabricated counterpart. • Reaction between Ti cores and Al maxtrix to form τ2 continues during solutionization. • (Al, Si) 3 Ti phase in the shells transforms into τ2-phase during solutionization. • Rsing partial remelting temperature enhances the above behaviors. • Rising partial remelting temperature decreases the solubility of Si in α-Al. • Tensile properties first increase and then decrease as the temperature exceeds 595 °C. [ABSTRACT FROM AUTHOR]

Purpose: Multivariate analysis of T2-weighted signal, diffusion ADC, and DKI parameters and tractography were used to differentiate chronic non-specific low back pain (CLBP) patients and asymptomatic controls (AC).Methods: A total of 30 patients with CLBP and 23 AC underwent diffusion kurtosis imaging (DKI) of lumbar spine with a 3T MRI scanner to get the ADC values and seven parameters of DKI in the nucleus pulposus (NP) of the intervertebral disc. The tractography and the tract-related parameters as other parameters were also generated to indicate the intactness of annulus fibrosus (AF). T2-grades of the discs were also quantified based on an eight-grade degeneration grading system. ADC and T2-grades were compared with DKI parameters for the differentiation of CLBP and AC groups.Results: There was no difference in the T2 grades, ADC value, and multiple parameters in DKI of NP between CLBP and AC groups (P > 0.05). The average FA values in NP in AC group were found significantly higher than in the CLBP group (P < 0.05). The scores for the intactness of AF of the intervertebral discs were significantly different in CLBP and AC groups, with 90% of sensitivity and 70% specificity (P < 0.05). Additionally, there were significantly differences in the length and volume values of the AF in CLBP and AC groups (P < 0.05).Conclusion: DKI is a good noninvasive method, and it might help to differentiate CLBP from AC. Particularly, the continuation of DKI tractography reflects the presence of annulus fibrosus fissures, an important character in the generation of the low back pain. These slides can be retrieved under Electronic Supplementary Material. [ABSTRACT FROM AUTHOR]

At present, most of the research work aims to optimize the technological parameters of laser derusting under the condition of without damaging the metal substrate. The surface microstructure and corrosion resistance of the 35# carbon steel metal substrate were investigated by selecting an appropriate laser power density without affecting laser derusting effect. The surface microstructure and topography were characterized by scanning electron microscope, metallographic microscope, and white light interferometer. X-ray diffraction method was used to determine the surface structure of original new samples and derusting samples. The microhardness of the cross-section of the metal substrate after laser derusting was measured by Vickers microhardness tester with the load of 0.098 N. The polarization curves and galvanic corrosion measurement curves were used to characterize the corrosion resistance of laser derusting samples and original new samples. It is found that a heat-affected layer (HAL) of about 25-μm depth was formed on the surface of the metal substrate after laser derusting, which was composed of ferrite and pearlite-like. And the hardness of the HAL was increased. Comparing with the original new samples, the corrosion resistance of the derusting samples was significantly improved due to the change of the surface microstructure. As a common structural steel, 35# carbon steel is easily corroded. It really has great significance if its corrosion resistance could be improved while the rust layer on the surface is removed by the laser derusting technology. [ABSTRACT FROM AUTHOR]

Objective: Our aim was to assess the microstructural changes of intervertebral disc degeneration induced by annulus needle puncture in rats by diffusion kurtosis imaging (DKI).Methods: Eighteen rats (36 discs) were punctured percutaneously at the intervertebral disc between C6/7, C7/8 (C-coccygeal vertebrae) with a 21-gauge needle. The rats were divided into six groups according to the time after the puncture: 3 h, 48 h, 3 days, 7 days, 10 days and 14 days. There were six discs in three rats in the control group. The rats' tail was imaged at 3T MRI with T2-weighted and diffusion-weighted and diffusion kurtosis imaging (DWI)/DKI sequences. The discs were categorized using a five-grade degeneration system based on the T2 images. The height of the discs and the parameters in DWI/DKI were measured and compared between the different time points. The histological images were also obtained from the discs.Results: The histological study revealed that the discs in the rat of the punctured groups were degenerated. The T2 grades of different groups presented an increasing trend from 7 to 10 days after puncture (R2 = 0.9424, P < 0.001), while the DWI/DKI parameters changes were consistent with the histological changes at the different time points and showed significant differences between the different groups (P < 0.05).Conclusions: DKI provides quantitative assessment of the microstructure changes of disc degeneration, and it is a non-invasive method. The DKI multi-parameter analysis is sensitive to discs changes caused by puncture. These slides can be retrieved under Electronic Supplementary Material. [ABSTRACT FROM AUTHOR]

An experimental investigation was performed to study the fatigue behavior of plain-weave fiber fabrics reinforced C/C-SiC composites (2D C/C-SiC composites) prepared by liquid silicon infiltration (LSI) under dynamic flexural stresses at room temperature. The results indicate that the fatigue limit (10 5 cycles) of 2D C/C-SiC composites subjected to flexural fatigue stresses is 95 MPa, corresponding to approximately 78% of flexural strength of virgin specimens. Moreover, as the fatigue loading/unloading proceeds, both strength enhancement and strength degradation are successively observed in the post-fatigue specimens under quasi-static flexural tests. Maximum residual flexural strength (RFS) of post-fatigue specimens increases to 135.7 MPa when the 2D C/C-SiC specimens are exposed to maximum fatigue stress of 95 MPa for 5000 cycles. The microstructures and fractured surfaces indicate that evolution of RFS is determined by the interaction of matrix cracking and interfacial degradation. The interfacial debonding and relief of residual thermal stresses induced by matrix cracking are mainly responsible for the enhanced strength in the post-fatigue specimens. [ABSTRACT FROM AUTHOR]

Three contents of zinc oxide (2 wt %, 4 wt % and 6 wt %) were added into raw BaTiO 3 powders. The maximum relative permittivity value (ε r ) is in the range 230–406 and the dielectric loss (tanδ) varies between 0.18 and 0.09 for all ZnO modified BaTiO 3 coatings for frequency1 kHz at ambient temperature. The reasons for enhancing the relative permittivity are attributed to the elimination of micro-cracks and pores. The detail discussion was conducted on the characteristics morphologies (cross section, fracture surface and spreading behavior of BaTiO 3 +xwt. % ZnO composite powders) and phase. With the analysis, the addition of ZnO leads to the improvement in the melting state and increment in amorphous phase. Zn existed in the form of secondary phase (ZnO) and substitution in the BaTiO 3 lattice. The enhancement in structure and dielectric performance is highly discussed based on the phase equilibria and chemical defect. [ABSTRACT FROM AUTHOR]

Nanocrystallization is a promising way to increase the toughness of brittle materials. In this work, to obtain toughened Fe 2 B coating and overcome various limitations of boriding, electro-spark deposition (ESD) has been used to prepare nanocrystalline Fe 2 B coating. A coarse-grained Fe 2 B electrode was used as anode. The microstructure, microhardness, nanomechanical properties and fracture toughness of the coating and the electrode material were comparatively investigated. Results showed that a metallurgically fused nanocrystalline Fe 2 B coating with few defects is obtained by ESD. Compared to the anode, the coating contains more Fe 3 B phase and a new phase of martensite. Moreover, the coating consists of planar crystals, cellular crystals, cellular dendrites, columnar dendrites and equiaxed dendrites due to the solidification conditions, and the grain size of the cellular crystals and the dendrites ranges from few tens of nanometers to several hundred nanometers. The transition zone between the coating and the substrate is the molten zone of the substrate, and the microstructure of this zone is greatly refined. The nanocrystalline Fe 2 B coating has improved fracture toughness while it has reduced hardness and Young's modulus, and some structures of the coating are remarkably toughened. [ABSTRACT FROM AUTHOR]

The microstructures, phase transformations, mechanical properties and shape memory effect of Ti-20Zr-10Nb-xAl (x=1, 2, 3, 4 at%) alloys were investigated. The X-ray diffraction results show that the alloys are composed of a single martensitic α″-phase and that the corresponding unit cell volume decreases with increasing Al content. The reverse martensitic transformation start temperature ( A s ) of the Ti-20Zr-10Nb-Al alloy is 534 K and decreases with increasing Al content. The addition of Al results in solid solution strengthening and grain refinement strengthening, thus improving the mechanical properties and the shape memory effect of the Ti-20Zr-10 Nb-xAl alloys. The Ti-20Zr-10Nb-3Al alloy shows the greatest shape memory strain (3.2%) and the largest tensile strain (17.6%) as well as a very high tensile strength (886 MPa). [ABSTRACT FROM AUTHOR]

Microstructure and corrosion behavior of the Ti-6Al-4V- x Zr ( x = 0, 10, 20, 30, 50 wt.%) alloys were investigated. Zr additions in the Ti-6Al–4V alloy promote the formation of martensitic phase. The width of α lamellae decreases and the β phase content increases with the increase of Zr content. The corrosion behavior of the alloys with various Zr content are significantly different. The passivation ability of Ti-6Al-4V- x Zr alloys increases with increasing Zr content. For the Ti-6Al-4V-30Zr and Ti-6Al-4V-50Zr alloys, a sudden increase in the current density occurred, which is caused by pitting corrosion. [ABSTRACT FROM AUTHOR]

The Al–Cu–Mg–Ag single crystal is prepared to study its precipitation behavior during aging under elevated compression stresses. Transmission electron microscopy (TEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and hardness test are used for this investigation. The results show that a compression stress of 50 MPa leads to more uniform length distribution but slightly lower number density of Ω-phase in the stress-aging sample, as compared to that of the stress-free aging sample. When a higher compressive stress of 200 MPa is applied, the number density of Ω-phase is significantly decreased while a large number density of θ’-phase are precipitated along the dislocation lines introduced by the applied stress. Furthermore, the stress-orientating effect on Ω precipitation can not be observed in Al–Cu–Mg–Ag single crystal during stress aging even under the compressive stress of 200 MPa loading along the [ 2 ¯ 15 ] Al direction. This result signifies that the applied stress magnitude is not the only critical factor in determining whether the stress-orienting effect of Ω-phase can be generated, as this effect may be also associated with the loading orientation during stress aging. [ABSTRACT FROM AUTHOR]

The precipitation behavior and property of Al Cu alloy during stress aging under various loading orientations were investigated using single crystals. The resulting microstructures and the strength property were examined by transmission electron microscope (TEM) and compression test, respectively, and the effect of the distribution of θ′-plates on strength property were discussed. The results show that the precipitation distribution of θ′ was significantly affected by the loading orientation during stress aging of Al Cu single crystals. Loading along close to 〈011〉 Al directions provided more uniform precipitation distribution of θ′ as compared to loading along close to 〈001〉 Al directions, and therefore provided higher strengthening stress of the θ′-plates for the stress aging sample. The results suggested that regulating the distribution of θ′ and therefore improving strength property are possible via controlling the loading orientation during stress aging. [ABSTRACT FROM AUTHOR]

In this study, Mo 2 FeB 2 -based cermet coating has been attempted to produce by electrospark deposition (ESD) process on a high speed steel substrate. Microstructural morphology, elementary distribution, phase constitute, microhardness, and wear resistance of the coating were investigated by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), microhardness measurement and tribological test. The SEM and EPMA results show that the coating is dense, metallurgically bonded to the substrate, and has an average thickness of 48.1 μm. Moreover, a discernible composition transition zone appeared between the coating and the substrate. The XRD patterns reveal a microstructural transformation from Mo 2 FeB 2 phase and binder phase (ferrite) of the cermet to amorphous phase and martensitic phase of the coating during the deposition, and the martensitic phase has nanocrystalline structure (31.7 nm). Such microstructure of the coating results in higher microhardness, lower friction coefficient, and better wear resistance than the high speed steel substrate. The main wear types for the coating are abrasive wear and fatigue wear. [ABSTRACT FROM AUTHOR]

To improve the corrosion resistance of micro-arc oxidation (MAO) treated Mg alloy wires, carbon (C) nanoparticles were added to the silicate electrolyte to fabricate C-containing composite coatings. Comparisons of microstructure, corrosion resistance and mechanical properties of uncoated wires, MAO-C-free coated wires and MAO-C coated wires were performed. The results indicated that the surface layers of Mg alloy wires treated with MAO were primarily composed of MgO and Mg 2 SiO 4 phases and demonstrated porous morphologies. The C nanoparticles in the electrolyte were capable of incorporating into composite coatings, forming a dense composite coating microstructure and resulting in the formation of a small amount of MgAlO 4 and Mg 3 SiO 4 F 2 , which improve corrosion resistance in static and dynamic immersion environments. Measurements of mechanical properties demonstrated that the MAO-C coated wires retained a high tensile strength of 180 MPa, even after dynamic immersion for 50 days, and possessed better corrosion resistance than the wires coated with MAO-C-free coating. The effects of shear stress and localized environment changes resulting from the flowing corrosive media were proposed as two mechanisms that accelerated corrosion in a dynamic immersion environment. [ABSTRACT FROM AUTHOR]

Due to the long-term cold and heat cycle of gray cast iron parts, thermal fatigue phenomena, such as cracks, locally occur during the service process, resulting in the scrapping of the entire parts. If these defects are surface treated, it will help save energy, reduce emissions, and promote the development of the circular economy. In this study, the Ni60 + Mo coating was prepared on gray cast iron by plasma cladding. The microhardness, microstructure, constituents, thermal fatigue properties, and corrosion wear performance of the cladding layer were analyzed by the microhardness tester, scanning electron microscopy, x-ray diffraction, and thermal fatigue test. The results show that the Ni60 + Mo coating can effectively inhibit the crack propagation and improve the thermal fatigue performance of the cladding layer. Meanwhile, the addition of the Mo element can enhance the diffusion degree of alloying elements in the cladding layer, improve the microstructure uniform, reduce segregation, and promote the formation of equiaxed grain in the cladding layer. With the increase of the Mo element, the average hardness of the plasma cladding layer gradually increases, the fatigue cracks growth rate decreases, the matrix hardness decay value slowly decreases, and the simple wear and corrosion wear properties all decrease. The Ni60-4.5wt.% Mo coating has the best performance. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the influence of various heat-pressing procedures (different holding time and heat pressing temperature) on the microstructure and flexural strength of lithium disilicate glass ceramic. An experimental lithium silicate glass ceramic (ELDC) was prepared from the SiO2-Li2O-K2O-Al2O3-ZrO2-P2O5 system and heat-pressed following different procedures by varying temperature and holding time. The flexural strength was tested and microstructure was analyzed. The relationships between the microstructure, mechanical properties and heat-pressing procedures were discussed in-depth. Results verified the feasibility of the application of dental heat-pressing technique in processing the experimental lithium disilicate glass ceramic. Different heat-pressing procedures showed significant influence on microstructure and flexural strength. ELDC heat-pressed at 950℃ with holding time of 15 min achieved an almost pore-free microstructure and the highest flexural strength, which was suitable for dental restorative application. [ABSTRACT FROM AUTHOR]

In order to prepare the PbTiO3 coating with high density and excellent piezoelectric properties on all kinds shape surface, the PbTiO3 coating was prepared by supersonic plasma spraying. The microstructure and mechanical properties were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectrograph (XPS). The dielectric constant and dissipation constant of the PbTiO3 coating were tested. The results show that the coating has a single ferroelectric phase with perovskite structure, and its surface is smooth and dense. In the course of spraying, about 50% PbTiO3 is decomposed into PbO and TiO2 at high temperature. The ferroelectric hysteresis is weak and the ferroelectric hysteresis loop is not completely closed, which indicates that the defects, such as pores and cracks, exist in the coating. Although the defects are inevitable, the PbTiO3 coating with ferroelectric and piezoelectric properties is successfully prepared. [ABSTRACT FROM AUTHOR]

• Heterogeneous microstructure was easily formed by DDRX during hot rolling. • Different storage energy can cause uneven grains during SA at high temperature. • Larger grains continued to annex adjacent smaller grains for the abnormal growth. • Adopting stepped heating from low to high temperatures can obtain uniform grains. Series of solution annealing experiments and quasi in-situ observation were employed to investigate the grain growth behaviors based on the heterogeneous microstructure with deformation bands and dynamic recrystallization (DRX) grains in hot rolled 316H austenitic stainless steel (ASS). It was worked out that during early stage of direct heating at high temperature of above 1000℃, the initial static recrystallized grains with different sizes would nucleate rapidly on the deformation band and DRX grains. With the extension of holding time, they gradually grew up to develop into the grains with large size differences, during which the larger grains continued to swallow adjacent smaller grains even presenting abnormal annexation or growth. However, by adopting stepped heating from low to high temperature, the grains evenly grew and presented relatively uniform distribution, which provides new idea for regulating grain size in manufacturing heavy ASSs. [ABSTRACT FROM AUTHOR]

In the paper, the effect of niobium addition on the microstructure, mechanical properties and wear resistance of high chromium cast iron has been studied. The results show that the microstructure of the heattreated alloys is composed of M7C3 and M23C6 types primary carbide, eutectic carbide, secondary carbide and a matrix of martensite and retained austenite. NbC particles appear both inside and on the edge of the primary carbides. The hardness of the studied alloys maintains around 66 HRC, not significantly affected by the Nb content within the selected range of 0.48%-0.74%. The impact toughness of the alloys increases with increasing niobium content. The wear resistance of the specimens presents little variation in spite of the increase of Nb content under a light load of 40 N. However, when heavier loads of 70 and 100 N are applied, the wear resistance increases with increasing Nb content. [ABSTRACT FROM AUTHOR]

The precipitation behaviour and age-hardening response of Al–1.5Cu–4.0Mg (wt.%) alloys microalloyed with Si have been investigated by means of hardness measurement, TEM and HRTEM. Compared to the ternary alloy, the quaternary alloys exhibit a higher hardness. It is found that the underaged microstructure in the Al–1.5Cu–4.0 Mg alloy contains some fine precipitates, which are identified as the T phase by FFT spectra. The peak-aged microstructures of the ternary alloy is dominated by the T phase, while the peak-aged microstructures of the Si-containing alloys are dominated by the S phase. The volume fraction of the S phase is found to increase as more Si is added. [ABSTRACT FROM PUBLISHER]

Abstract: The effects of alkaline earth ions as network modifiers on the broad near infrared (NIR) emission from bismuth doped aluminophosphsilicate glasses were investigated. The results showed the intensity of NIR emission peaked at 1300 nm increased with increase in the radius of alkaline earth ions, while those of NIR emission peaked at 1100 nm and red emission from Bi2+ vary in an opposite tendency. We propose that particular emission performance of Bi result from the abnormal reduction phenomenon of Bi ions by SiO2–P2O5–Al2O3–RO (R = Mg, Ca, Sr, Ba, SPAR) glass hosts, which became effective with the order of MgO–CaO–SrO–BaO. Then the origins of infrared-emitting bismuth centers were discussed according to the effect of alkaline earth ions on the conversion of Bi ions. [Copyright &y& Elsevier]

Abstract: Titanium and its alloys are promising biomedical metal materials. In order to improve the bioactivity of TiO2 coatings, three processes including micro-arc oxidation (MAO) in a Ca and P ion electrolyte (Ti-MAO), MAO in a 1M NaOH electrolyte (Ti-NaOH) which was heated to 60°C and a two-step MAO process in which specimens were first treated by MAO in Ca and P ion solution and then further in a 1M heated NaOH electrolyte in succession (Ti-MAO-NaOH) were carried out. Round pores were found to form on the surface of the Ti-MAO sample while homogeneously distributed hollow spherical particles were found on both the Ti-NaOH and Ti-MAO-NaOH sample surfaces. The bioactivity evaluation showed that the combination of MAO processes in different electrolytes induced more rapid formation of apatite in contrast to the simple MAO treatment in heated alkaline electrolyte. The Ti-OH groups formed in alkaline electrolyte are found to be response for the rapid formation of hydroxyapatite during a SBF soaking. The previous introduction of Ca and P can increase the opportunity to form hydroxyapatite. [Copyright &y& Elsevier]

Nanocrystalline Ni1− x Zn x Fe2 O4 (0 ≤ x ≤ 1.0) powder with grain size of 30 nm was prepared using the spraying-coprecipitation method. The obtained nanocrystalline Ni1− x Zn x Fe2 O4 powder was sintered using conventional and microwave sintering techniques. The results show that the microstructure and magnetic properties of the sintered samples are obviously improved by microwave sintering of nanocrystalline Ni1− x Zn x Fe2 O4 ferrite powder. The initial permeability of Ni1− x Zn x Fe2 O4 ferrite increases with the increase in zinc concentration, although its resonance frequencies shift from high frequency to low frequency. The maximum initial permeability for microwave-sintered Ni0.4 Zn0.6 Fe2 O4 ceramic obtained at the temperature of 1170°C for 30 min reaches up to 360.9, and its resonance frequency is ~10 MHz. It may be attributed to the nanocrystalline Ni1− x Zn x Fe2 O4 raw powder as well as the microwave sintering process, which results in a synergistic effect on improvement of the microstructure and magnetic properties. [ABSTRACT FROM AUTHOR]

Abstract: Heat transfer and dynamic fluid flow have been calculated to predict hybrid laser-arc weld pool geometry by establishing a three-dimensional numerical model. Based on previous analytical methods, a mathematical model and a general procedure are extended for calculating the fraction of misoriented stray grains in hybrid laser-arc welds. Solidification microstructures in hybrid welds in single-crystal materials are evaluated by combining the crystallographic orientation of growing dendrites with the solidification front orientation that is derived from a geometric model of the dendritic growth pattern. It is shown that finer dendrite arm spacing is always found near the solid–liquid boundary of the top side of the weld or weld root, and the coarsest dendritic microstructure occurs in the center of the weld crown. It is also found that a higher welding speed and a lower arc current or laser power are beneficial to the minimization of stray-grain formation. Calculated weld geometries are compared to previous experimental work, and calculated dendrite arm spacing agrees reasonably well with the experimental result. [Copyright &y& Elsevier]

Abstract: SiO2-coated Ca2BO3Cl:Eu2+ phosphors were prepared by the sol–gel method in order to enhance the chemical and thermal stabilities of Ca2BO3Cl:Eu2+ phosphor. The phase structures, microstructures and luminescence properties were studied by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrometer, respectively. The emission intensity of SiO2-coated Ca2BO3Cl:Eu2+ phosphor decreased a little compared to that of the uncoated phosphor. The moisture resistances of the phosphors were comparatively examined by the aging treatment experiment in the water, and the thermal stability was studied by the temperature dependent photoluminescence spectra. The results indicated that SiO2 coating on the surface of the phosphor particles improved the moisture-resistance and thermal stability to a large extent. [Copyright &y& Elsevier]

Abstract: Well-dispersed hydroxyapatite (HA) nanorods with different morphologies were synthesized by a hydrothermal method in oleic acid, ethanol and water reaction system, and the surfactant assisted modifications effect was also comparatively studied. The structure and morphology of samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM), respectively. The effect of reaction systems and surfactant additives on the morphology evolution of HA nanorods were discussed in detail. The results showed that the controlled experimental conditions in the systems, such as the content ratio of oleic acid/ethanol, pH value and the content ratio of Ca/P source had an significant effect on the morphology evolution of as-prepared HA nanorods. Further, the selected surfactant additives, such as cetyltriethylammnonium bromide (CTAB), sodium dodecyl sulfate (K12) also play an important role in the formation of the uniform morphology of HA nanorods. Some possible formation mechanisms of the HA nanorods in the present reaction systems is proposed. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous polycrystals of hydroxyapatite-calcium are synthesized via a modified hard-templating route. The structure properties of hydroxyapatite-calcium are characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and N2 adsorption–desorption isotherms. Wide-angle X-ray diffraction and Fourier transform infrared spectroscopy measurements reveal that the crystalline grains consist of highly crystalline pure hydroxyapatite phases. Transmission electron microscopy results show that rod-like hydroxyapatite-calcium grains with an average diameter of about 100nm long and about 20nm wide are uniformly distributed, which are also observed with an average pore size of 2–3nm. Based on N2 adsorption–desorption isotherms investigation, the pore size, surface area and pore volume of mesoporous hydroxyapatite-calcium are 2.73nm, 42.43m2 g−1 and 0.12cm3 g−1, respectively. [Copyright &y& Elsevier]

The influence of high strain rate on the precipitate microstructure in impacted aluminum alloy was revealed by transmission electron microscopy. The estimated aspect ratio and the area fraction of θ′ precipitate in impacted aluminum alloy specimens were not dramatically changed until impact testing at 5730s−1 or higher at ambient temperature although the hardness of specimens impacted at 667–7050s−1 was decreased. High strain rates are thus a simple way to lower the transformation temperature of θ′ phase in impacted aluminum alloy. [Copyright &y& Elsevier]

The structural, dielectric, ferroelectric and piezoelectric properties of 0.59Pb(Mg1/3Nb2/3)O3–0.31PbTiO3–0.10Pb(Fe1/2Nb1/2)O3 (0.59PMN–0.31PT–0.10PFN) ceramic have been investigated. The investigations show that its phase structure is near the morphotropic phase boundary, and excellent electrical properties are obtained with this composition. Compared with PMN–PT, studies also show that 10% PFN substitution results in (i) a decreased sintered temperature; (ii) an increased Curie temperature and peculiar relaxation behavior; and (iii) a low dielectric loss, which indicates that the novel ternary system deserves further exploration. [Copyright &y& Elsevier]

The microstructural evolution and ageing behaviour of Al–4.0Mg–1.5Cu–1.0Li–(0.2Sc)–0.12Zr alloys were investigated. The results indicate that small addition of Sc can enhance the ageing strengthening effect while the time taken to the ageing peak is prolonged. And the Sc-containing Al–4.0Mg–1.5Cu–1.0Li–0.2Sc–0.12Zr alloy exhibits a promising combination of strength and ductility. TEM observations show that the precipitation processes during ageing can be modified by the small addition of Sc. [Copyright &y& Elsevier]

Ceramic particle reinforced medium entropy alloys (MEAs) coatings have attracted considerable attention because of their excellent hardness and wear resistance. In this study, (CoCrNi) 94 Al 3 Ti 3 MEA coating and (CoCrNi) 94 Al 3 Ti 3 -cBN MEA composite coating were prepared by high-speed laser cladding. The phase constituents, microstructure，hardness and wear mechanisms of the two coatings were investigated using XRD, Raman spectra, SEM, EDS, and TEM. Results show that (CoCrNi) 94 Al 3 Ti 3 comprises only simple FCC phase because of the high-entropy effect. However, the addition of cBN transforms the phase from FCC to FCC + BCC, but also generates micron-scale TiN and CoCr, as well as nanoscale TiN and CrB. In addition, part of the cBN is converted to hBN with lubricating effect under high energy laser. As for the properties, compared with (CoCrNi) 94 Al 3 Ti 3 coating, (CoCrNi) 94 Al 3 Ti 3 -cBN coating exhibits increased hardness by 2.2 times, increased wear resistance by 5.6 times, and decreased friction coefficient from 0.58 to 0.47. It is expected that this research will provide research ideas for the preparation coating of friction reduction and wear resistance performances on titanium alloy surfaces. [ABSTRACT FROM AUTHOR]

In this study, the martensitic stainless-steel powder had been successfully deposited on the surfaces of 1045 wrought steel substrates using five types of laser metal deposition strategies. The results showed that a thin buffer layer can be naturally generated in-between the deposition layer and substrate owning to the dilution effect, producing functionally graded structures consisted of martensite dendrite matrices and intermetallic phases (e.g., M 23 (C, B) 6). Unfortunately, the poor deformation characteristic of natural buffer layers can exacerbate the risk of cracking, leading to an incompatibility between martensitic stainless steel and forming steel. A thick artificial buffer layer was then designed by addition of Inconel 625 powder. Because of the formation of graded austenite phase in the artificial buffer layer, the yield strength of specimen was enhanced significantly. Hence, our study can be used for manufacture of reliable moulds with high surface hardness and structural strength and may be helpful in further developing hybrid forming strategy in the field of mould manufacture. When subjected to stress impact during mould filling, the artificial buffer layer with functionally graded properties would have a perfect capability to bear the deformation as the load increased, dramatically improving the reliability and functionality of moulds. Unlabelled Image • The buffer layers was formed due to the dilution effect. • The artificial buffer layer had perfect functionally graded properties. • A hybrid mould with artificial buffer layer was fabricated by LMD. [ABSTRACT FROM AUTHOR]

• An independently developed nickel-based superalloy powder was deposited by laser engineered net shaping. • The as-deposited of a nickel-based superalloy with the crack-free structure was obtained. • The microstructure evolution and formation mechanism of the crack-free structure is proposed. In this study, the crack-free parts have been successfully fabricated by Laser Engineered Net Shaping (LENS) based on a Ni-Co-Cr-Al-Ti-Fe-Nb-Mo nickel-based superalloy powder, and its microstructure evolution and formation mechanism were investigated. The results revealed that the microstructure along the deposition direction is stray dendrites with disordered growth direction in the bottom two layers, epitaxially growing elongated columnar dendrites dominating the whole cross-section of the as-deposited, fine equiaxed grains in the upper of the last layer, respectively. Moreover, it can be found that although the as-deposited layer contains many high angle grain boundaries, no cracks can be observed. According to the chemical composition and phase analyses, it can be concluded that crack-free microstructure is ascribed to the homogeneous distribution of elements and the formation of single-phase γ in the as-deposited. The effect of 1.34 Al, 1.37 Ti, 0.41 Nb, and 0.50 Mo (wt%) on the formation of low melting point substances is discussed. The room-temperature ultimate tensile strength is about 807 MPa, while the high-temperature ultimate tensile strength is 654 MPa. [ABSTRACT FROM AUTHOR]

Abstract: The structure of 20GaF3–15InF3 –20CdF2–15ZnF2–20PbF2–10SnF2 glass (GICZPS) was studied by EXAFS and XRD. The results indicate that Ga3+ is more stable than In3+ in the GICZPS glass network, and Zn2+ is the glass modifier, the coordination number of which is 6. [Copyright &y& Elsevier]

A new approach to the stimulation of atomic clustering reactions shows potential to address the 'strength-ductility trade-off' in Al–Cu–Mg alloys. The evolution of the alloy microstructure during this thermomechanical processing was followed carefully using electron microscopy, X-ray diffraction, and atom probe microscopy. The distributions of the Mg and Cu solute atoms, and the characteristic distributions of Mg–Cu co-clusters, were investigated in detail. The factors affecting the strength of the alloy were assessed semi-quantitatively and the results suggest that Mg–Cu atom co-clusters contribute significant strengthening in this Al–Cu–Mg alloy, when subjected to this thermomechanical processing. The novel introduction of asymmetric rolling into the thermomechanical process increases the overall strength and we propose that this is due to the synergistic effects of cluster strengthening, dislocation strengthening, and texture engineering. The significant improvement in plasticity is attributed to a combination of the shear texture, the relatively high ratio of low-angle grain boundaries, and the avoidance of microstructural stress and strain concentrations such as those often associated with precipitation and precipitate-free-zones. [ABSTRACT FROM AUTHOR]

The microstructure evolution, mechanical properties, and tribological properties of high boron cast steel (HBCS) with various Mo concentrations are investigated. The results indicate that Mo addition can significantly modify the microstructure and enhance the comprehensive properties. With the increase of Mo concentration, borides change from the original fish-bone Fe-rich and Cr-rich M2B to dendritic Fe-rich M2B, blocky and cluster-like Cr-rich M2B, and grainy Mo-rich M2B. The hardness of HBCS increases gradually with the increase of Mo content due to the solid solution strengthening and the refinement of M2B. It can be found that all the samples exhibit quasi-cleavage, but the impact toughness increases firstly and reaches the maximum value when the concentration of Mo is 2.10 wt.%, which is the result of the dispersive distribution of M2B rather than the original fish-bone M2B. Subsequently, the impact toughness begins to decrease as the concentration of Mo further increases because of the extensive formation of grainy Mo-rich M2B at the grain boundary. Meanwhile, the wear results reveal that the average friction coefficient and wear ratio decrease with the increase of Mo content, and the wear mechanism changes from abrasive wear and adhesive wear to abrasive wear when the concentration of Mo exceeds 2.10 wt.%. [ABSTRACT FROM AUTHOR]

Examines the effect of lithium on the aging characteristics and microstructures of aluminum-copper-magnesium-silver alloys with low copper:magnesium ratio. Alloys preparation by melting and casting under argon atmosphere; Indication that low copper:magnesium ratio aluminum-copper-magnesium alloys containing silver and lithium exhibit promising properties; Implication that the alloy possesses higher tensile properties.

• The spall strength of tungsten alloy is weakly dependent on the peak stress. • With the increase of impact stress, cleavage fracture replaces intergranular fracture as the main fracture mode. • Twins appear near the crack of tungsten particles, which hinders the further propagation of cracks. • The {100}, {110} and {111} planes are the most potent macroscopic cleavage planes for the tungsten alloy. In this study, plate-impact experiments are conducted using tungsten heavy alloy (WHA) to obtain the free-surface velocity profiles under shock stress of 6–23 GPa. By analyzing the velocity wave profile, it is demonstrated that the spall strength is weakly dependent on the peak stress. The microstructure of the recovered WHA is well characterized and it's observed that intergranular fracture and cleavage are the primary fracture mechanisms. Deformation twins are sparsely distributed near the cleavage crack. The existence of twin boundary not only affects crack propagation but also regulates the crack path and reinitiates the cleavage propagation direction on the twin boundary. The macroscopic cleavage facet planes are detected to be {100}, {110} and {111} at all shock stress. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the effect of aluminum addition on the microstructure and mechanical properties of Mg-8Gd-4Y-1Zn alloy. Design/methodology/approach: Mg-8Gd-4Y-1Zn-xAl (x = 0, 0.5, 1.0, 1.5, 2.0 Wt.%) alloys were prepared by the conventional gravity casting technology, and then microstructures, phase composition and mechanical properties were investigated by material characterization method, systematically. Findings: Results show that the as-cast microstructure of Mg-8Gd-4Y-1Zn alloy mainly consists of a-Mg matrix as well as Mg12REZn (18 R LPSO structure), and island-like Mg3(RE, Zn) phase is distributed at the grain boundary. The addition of a small amount of Al (0.5 Wt.%) can decrease the content of island-like Mg3(RE, Zn) phase, but significantly increase the content of long-period stacking ordered (LPSO) structure, resulting in the improvement of both tensile strength and elongation of Mg-8Gd-4Y-1Zn alloy. However, the addition of excessive Al will consume Re element and decrease the amount of LPSO structure, leading to the decrease of tensile properties. When the content of Al is 0.5 Wt.%, the tensile strength and elongation are 225 MPa and 9.0% of Mg-8Gd-4Y-1Zn alloy, which are 14% and 29% higher than that of Mg-8Gd-4Y-1Zn alloy, respectively. Originality/value: Adding aluminum to Mg-8Gd-4Y-1Zn alloy strengthens its mechanical properties. And the effect of Al content on the alloy strengthening. The formation mechanism of LPSO structure with different aluminum content was revealed. [ABSTRACT FROM AUTHOR]

1–9 wt% of ZrB 2 particles are added to Cu to produce ZrB 2 /Cu composites by a hot-pressed sintering process. Microstructures, mechanical and electrical properties of the prepared ZrB 2 /Cu composites are systematically investigated. The results indicated that the relative density and electrical conductivity of the composites decrease with increasing ZrB 2 content. However, the microhardness reaches a maximum value of 100.8 HV 0.2 as ZrB 2 content increases to 7 wt % and then decreases when ZrB 2 content further increases. TEM study reveals that the hexagonal ZrB 2 crystals in size of several micrometers are well embedded in Cu matrix. The interfacial zone consists of both sharp interfaces and amorphous transition layer. Grain refinement strengthening, Orowan strengthening and coefficients of thermal expansion mismatch strengthening contribute to the increment of microhardness and reduce the electrical conductivity. [ABSTRACT FROM AUTHOR]

• Specific heat capacity of micro-fibre reinforced mortar was measured. • Effects of w/c ratio, fibre type and elevated temperature were considered. • A micromechanical model was developed to predict the effective specific heat. • Thermal expansion coupling effect on specific heat was quantitatively analysed. The temperature dependency of specific heat capacity is crucial for thermo-mechanical analysis of fibre reinforced cementitious composites. In this study, a combined experimental and theoretical analysis was conducted to characterise the role of micro fibres in tailoring the specific heat capacity of cementitious composites at elevated temperatures. The specific heat capacity of cement mortar reinforced with four types of fibres, including polypropylene, basalt, carbon and glass fibres, was measured by means of a transient method at up to 400 °C. Based on the effective medium theory, a multiscale homogenization model was developed to predict the specific heat capacity evolution of cementitious composite with temperature from micro to macro level. The results indicate that within the measured temperature range, the addition of 2.0 vol% polypropylene and glass fibres lead to the maximum rise or drop in specific heat capacity of mortar by 8.7% and 14.1%, respectively. In addition, the thermal expansion of polymer fibre was proved to effectively enhance the specific heat capacity of mortar due to thermal expansion coupling effect. The parametric analysis suggests that stiffer inclusions with high thermal expansion govern the effective specific heat capacity coupled with thermal expansion, while the composite incorporated with softer inclusions is insensitive to the variation in thermal properties of inclusions. [ABSTRACT FROM AUTHOR]

Cu matrix composites have received increased attention in a wide industrial area because of their excellent mechanical properties and good electrical and thermal conductivity. However, the addition of general ceramic reinforcements often leads to a marked reduction in electrical conductivity for Cu matrix composites. In this study, the ZrB2-reinforced Cu composites have been developed to overcome this drawback since these metal borides possess relatively high electrical conductivity. The 5 wt.% ZrB2/Cu composites were prepared using hot-pressed sintering techniques at varying temperatures from 760 to 920°C. The influence of sintering temperature on the microstructure, relative density, and mechanical and electrical properties was examined. The results of the SEM observation show that ZrB2 particles are seamlessly integrated into the Cu matrix for all ZrB2/Cu composites. The average grain size of the Cu matrix increases from 360 to 980 nm with the increase of the sintering temperature. The increase in sintering temperature also leads to the surface porosity decrease from 1.4 to 0.4%. The relative density and electric conductivity of the composites increase at the same time as the sintering temperature increases. However, microhardness increases and decreases, with a maximum value of 92 HV0.2 achieved at 840°C. The elastic modulus and nanohardness maps determined from the nanoindentation indicate that the reinforced ZrB2 particles demonstrate the highest values for elastic modulus (340–500 GPa) and nanohardness (30–48 GPa). At the same time, the Cu matrix possesses a modulus of 100–200 GPa and nanohardness of about 10 GPa. TEM observation confirmed that the sintering temperature exhibits little influence on the interface reaction between ZrB2 and Cu. Both sharp interface and interface with amorphous transition layer are observed. The variation of microhardness is mainly due to the strengthening of grain refinement and to the mismatch of the thermal expansion coefficients. The above results can provide further insights into the deeper understanding of the role of sintering temperature during hot-pressed sintering. [ABSTRACT FROM AUTHOR]

Owing to the light weight and high energy, the "All-aluminum engine" can reduce fuel consumption and pollutant emissions, showing a great significance in saving resources and protecting the environment, and becoming a research hotspot. However, the aluminum alloy cylinder liners have difficulty withstanding extremely harsh working conditions, such as strong friction and wear, making the engine extremely easy to damage. In this work, Al-25Si wear-resistant coating was deposited by inner hole supersonic plasma spraying technique to improve the wear resistance of the aluminum alloy cylinder liner. The microstructure, phase composition, mechanical properties and tribological properties were tested by SEM, XRD, tribological machine, etc. The results indicated that the coating exhibited an excellent bonding strength of 44.1 MPa, and the average hardness and average friction coefficient of the coating are 267.09 ± 14.85 HV0.2, and 0.20, respectively. The total wear amount, the wear scar width and the wear scar depth of the coating are 2.77 × 10−3 mm3, 654.3 μm and 8.95 μm, respectively, which showed that the coating can significantly improve the tribological properties of the "All-aluminum engine". The wear mechanism of the coating was mainly interpreted by furrow cutting, extrusion and spalling in two-body abrasive wear, three-body abrasive wear and a small amount of oxidative wear. [ABSTRACT FROM AUTHOR]

Very few micromechanical models are available for hybrid fiber reinforced concrete (HFRC), although it has been widely applied in many structures. To quantitatively predict the effective properties of HFRC with the aggregate and interfacial transition zone (ITZ) effects, a multi-phase micromechanical framework is proposed based on the material’s microstructures. In the proposed model, the multi-types of fibers, aggregate, cement paste and ITZ are comprehensively considered. The volume fraction of the ITZ is analytically calculated based on the aggregate grading. Multi-level homogenization schemes are presented to predict the effective properties of HFRC. By utilizing the generalized self-consistent approach, the equivalent matrix composed by the aggregate, cement and the ITZ between them are obtained with the first and second level homogenization procedures. Through adding different types of fibers step by step into the equivalent matrix, the properties of HFRC are reached with the modifications to the Halpin-Tsai model. To demonstrate the feasibility of the proposed micromechanical framework, the predictions herein are compared with the experimental data, the Voigt upper bound and the Reuss lower bound. Finally, the influences of aggregate, ITZ, multi-types of fibers on the properties of HFRC are discussed based on the proposed micromechanical model. [ABSTRACT FROM AUTHOR]

The temperature effect induced by tunnel fire is important in geotechnical engineering. Due to the difficulties of extinguishing a fire in a tunnel, the fire duration time could be more than 120 min and after the heating the temperature of the soil around the tunnel could exceed 100 °C. However, the physical and mechanical properties of soils exposed to temperatures in the range of 100 °C to 200 °C have been rarely explored. A custom high-temperature apparatus was developed for measuring soft clay specimens with variations of mass, moisture content, dimensions and temperature distributions exposed to high temperatures of 105 °C, 120 °C, 150 °C and 200 °C for 150 min and 240 min, respectively. These measurements are performed after high-temperature exposure, and the water in both liquid and vapor phases are allowed to escape the specimens when the pore pressure exceeds 100 kPa during the heating process. The results show that the volume change, saturation and dry density of the specimens vary nonlinearly with the ambient temperature and are affected by the exposure time. The results also show that the variation of temperature within the specimen may be divided into four stages characterized by a rapid temperature rise stage followed by a plateau at 100 °C with another rapid temperature rise and a final plateau corresponding to the ambient temperature. Finally, novel changes in particle agglomeration and cluster shapes of the exposed samples were observed using a Scanning Electron Micro-scope. [ABSTRACT FROM AUTHOR]

In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle volumetric fraction of ~38%. During solidification, interface reaction takes place between WC-Co particles and high chromium cast iron. Melting and dissolving of prefabricated particles are also found, suggesting that local Co melting and diffusion play an important role in promoting interface metallurgical bonding. The composite layer is composed of ferrite and a series of carbides, such as (Cr, W, Fe)23C6, WC, W2C, M6C and M12C. The inhomogeneous hardness in the obtained composite material shows a gradient decrease from the particle reinforced metal matrix composite layer to the matrix layer. The maximum hardness of 86.3 HRA (69.5 HRC) is obtained on the particle reinforced surface, strongly indicating that the composite can be used as wear resistant material. [ABSTRACT FROM AUTHOR]

• FeCrAlNbNi alloy zones were prepared on the surface of 304 stainless steel by laser surface alloying. • Nb segregated in the AZ and was mainly distributed in the interdendritic area. • In the process of oxidation at 900 °C for 100 h, the AZ had a slower oxidation rate than the substrate. • After oxidation at 900 °C for 100 h, the Al on the AZ surface did not appear depleted. To improve the high-temperature oxidation performance of 304 stainless steel and increase its service life, a FeCrAlNbNi alloyed zone (AZ) was prepared on the surface of 304 stainless steel through laser surface alloying, and the microstructure of the AZ was studied. The micromorphology of the AZ was mainly equiaxed dendrites, and the Nb element segregated in the interdendritic region. In addition, the AZ and substrate were subjected to isothermal oxidation experiments for 100 h at 900 °C. The AZ showed less weight gain and a lower oxidation rate, and it had better oxidation resistance than the substrate. In the early stage of oxidation, a less dense Al 2 O 3 oxide layer was formed on the surface of the AZ. As oxidation progressed, Al passed through the oxide layer to form aggregated Al 2 O 3 on the surface. In the middle of oxidation, the Al 2 O 3 oxide layer gradually became dense, and aggregated Al 2 O 3 began to scatter. In the late stage of oxidation, a stable, dense and continuous Al 2 O 3 layer was formed on the surface of the AZ with a thickness of approximately 1.2 µm. At the same time, energy dispersive spectroscopy showed that the Al under the oxide layer was not depleted, which indicates that the FeCrAINbNi AZ has excellent high-temperature protection performance. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new method to generate the random distribution of fibres in the transversal cross-section of fibre reinforced composites with high fibre volume fraction. The algorithm, named random sequential expansion (RSE) algorithm by the authors, is based on the hard-core model, but overcomes the jamming limit of hard-core model and is able to generate random distributions for high values of fibre volume fractions. By adjusting the inter-fibre distance parameters, it can generate microstructures with different fibre volume fractions expediently. Statistical analysis is performed on the generated distributions and a good agreement with the completely spatial random (CSR) pattern is found in all statistics analysed. Finite element analysis (FEA) is conducted to predict the effective properties of the generated microstructures. The predicted properties show reasonable agreement with the experimental results. The present algorithm is simple, highly efficient and provides a useful alternative to generate random numerical models that can be used in micromechanical analysis of composites. [Copyright &y& Elsevier]

Abstract: One dimensional bifunctional magnetic-photocatalytic CNTs/Fe3O4–ZnO nanohybrids were synthesized by one-pot polyol sequential process. The as synthesized products were characterized by X-ray diffraction, Fourier transform infrared spectrometer, transmission electronic microscope, energy dispersive spectrometer, physical properties measurement system and UV–Vis absorption spectroscopy. The results exhibit the ZnO forms heterogenerously on the surface of CNTs/Fe3O4 and the nanohybrids display superparamagnetic behavior at room temperature. Photocatalytic studies verify the as-prepared sample have high photocatalytic activity toward the photodegradation of methyl orange in solution. In addition, the photocatalyst can be recycled using magnetic field and maintain high photocatalytic activity. [Copyright &y& Elsevier]

Abstract: TaC/SiC composites with 5–40vol.% 6H–SiC were fabricated by spark plasma sintering at 1800°C for 5min. Effects of SiC concentrations on the densification, microstructure, and mechanical properties of the materials were investigated. The results showed the densification process of the TaC/SiC composites was composed of six sequent stages. SiC addition was effective in eliminating the closed porosities in the final stage to yield fully dense TaC/SiC composites at 20vol.% SiC concentrations and above. TaC grain sizes decreased with SiC concentration increase. The 40vol.% SiC composition had the highest flexure strength and fracture toughness up to 703MPa and 6.8MPam1/2 due to the reinforcement of the SiC agent. The TaC/SiC composites with 20 and 40vol.% SiC showed good flexural strength at 1400°C. [Copyright &y& Elsevier]

α-SiAlON/α-SiC composites with 0-40 wt% α-SiC were synthesized by spark plasma sintering for 5 min at 1800°C under 20 MPa pressure. A self-reinforcing microstructure with both elongated α-SiAlON and α-SiC grains, was formed. Flexural strength and fracture toughness were significantly improved due to the in situ reinforcement. High fracture toughness up to 8.2 MPa ∙m1/2 was obtained in the 40 wt% SiC composition. [ABSTRACT FROM AUTHOR]