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Ni-based alloys are resistant against wear and corrosion, and are widely applied in surface engineering. In this study, different amounts of graphite (0, 5 and 10 wt.%) are added to NiCrBSi powder as a solid lubricant. The pure and composite powders are deposited on 420 stainless steel through the high-velocity oxygen fuel process. The microstructure and properties of the coatings are examined through x-ray diffraction and scanning electron microscope. Vickers microhardness test is run for the coatings' hardness measurement. NiCrBSi has the highest hardness of 650HV. Hardness of the coatings decreases with the increase in the graphite content. The porosity measurement by ImageJ analyzer indicates that the NiCrBSi coating has the lowest porosity. To assess the ambient and high-temperature wear resistance of the coatings, ball-on-disk wear tests were run with 15 N load and the sliding distance of 1000 m at 25 °C and 450 °C. The results indicate that the NiCrBSi and NiCrBSi-10 wt.%Gr coatings have the highest wear resistance at ambient and high temperatures, respectively. The friction coefficient of the coatings containing lubricant is lower than that of the NiCrBSi coating. [ABSTRACT FROM AUTHOR]

Abstract In this paper, formation of uniform and large-area micro/nanostructures on pure aluminum surfaces using a continuous-wave laser irradiation is presented. Gold nanolayer coating was utilized as a confinement layer for controlling the possible hydrodynamic phenomena in a molten area. Dependency of the laser-induced morphology on the thickness of a gold coating was investigated in this regard. Scanning electron microscopy, energy dispersive spectroscopy, grazing test of the X-ray diffraction, and optical absorption/reflection spectroscopy in UV/visible/IR ranges were employed to characterize the samples. Results showed that the formation of uniform structures of average sizes of 50 nm-5 μm on aluminum surface was possible following the irradiation of a continuous-wave CO 2 laser, delivering 130 W beam power. Alterations of the surface morphology brought about an increase in specific absorption peaks at the UV region and the appearance of an absorption peak in the visible range. In addition, these structure-covered surfaces provided interesting reflection behaviors in different spectral areas, which can clearly reflect their high potential to be used as selective solar absorbers. The results of this investigation indicated that optical characteristics such as absorption and emission coefficients as well as ξ factor were 0.98, 0.13, and 7.53, respectively. It can therefore be concluded that this process can be considered an efficient and fast technique to fabricate selective solar absorbers. Highlights • Uniform micro/nanostructures formed on aluminum surface coated with gold nanolayer • Continuous-wave laser irradiation structuring • Evaluation of structural and optical features of the samples • Method with good potential for selective solar absorber manufacturing process [ABSTRACT FROM AUTHOR]

Abstract As cast FeCrCuMnNi high entropy alloys were heat treated at different temperatures and times. Structure and mechanical properties of the heat treated alloy were studied using X-Ray diffraction, tensile test, hardness test and scanning electron microscopy. It has been found that the FeCrCuMnNi has thermal stability in mechanical properties almost up to 600 °C. Nevertheless, the alloy revealed an unusual behavior after heat treating at higher temperatures. A sharp drop of the tensile strength, strain to fracture and work hardening capability occurred at temperatures between 700 °C and 800 °C due to formation of a hard σ phase in the alloy. The hardness follows a plateau in the 700–800 °C range and then softening continues, together with a decrease in strength and increase in ductility, due to dissolution of the hard σ phase and decreased amount of BCC phase. Highlights • BCC phase dissolves and FCC one grows due to high temperature heat treatment. • Formation of a σ phase at 800 °C, leads to a remarkable drop in tensile properties. • Hardening capacity decreases significantly as a result of σ phase formation. • Strain hardening rate decreases due to increasing the heat treatment temperature. • Increasing heat treatment temperature, leads to a more ductile fracture. [ABSTRACT FROM AUTHOR]

The effect of rare earth (RE) elements addition on the microstructure and high temperature mechanical properties of a β-stabilized TiAl alloy was investigated by scanning electron microscopy (SEM) and high temperature compression tests. SEM and EDS results showed that RE-added alloys contained dispersed particles. Most particles were rich in RE-elements and oxygen, thereby suggesting that solute oxygen atoms in the matrix of alloys were scavenged by RE-elements. However, less than 10% of particles contained oxide phase in proximity to aluminide phase. With increasing RE-content, mean size of particles was increased; however, the number of particles reached to the maximum values at 0.2% RE, corresponding to minimum interparticle spacing. Afterwards, as a result of increasing growth rate, the number of particles was declined to the lower values. Fine and closely spaced particles in the microstructure of TNM+0.2La and TNM+0.2Er alloys led to retarding dynamic recrystallization and higher peak flow stresses at 900 and 1000 °C. Also, the results showed that Er-containing alloys possessed a higher flow stress, particularly at 1000 °C, since the particle size of Er-containing alloys was less than that of La-containing alloys. [ABSTRACT FROM AUTHOR]

AISI D2 cold-work tool steel is usually used for the purpose of hardness and wear resistance. Thermoreactive diffusion coating (TRD) treatment can be applied to this type of tool steel to improve the surface hardness. Since the rollers made of D2 tool steels are susceptible to wear fatigue, its surface hardness is of critical importance. A vanadium carbide coating was applied to the D2 tool steel samples by immersion in a borax liquid bath containing ferrovanadium, aluminum, and boric acid. Coating process and hardening heat treatment were carried out simultaneously in two steps. Firstly the samples were preheated up to 500°C and then TRD coating was performed on the samples at various temperatures for different times. Secondly the samples were undergone a mar-tempering heat treatment cycle in which the samples were austenitized in a BaCl molten bath at 1070°C for 30 minutes, oil quenched and then a two stage tempering treatment was applied to the quenched samples. The surface hardness of the coated sample was evaluated as 2300-3200 HV at various conditions while the hardness of the bulk was measured as 670-720 HV. XRD analysis of the coating showed that the main component was vanadium carbide (VC). Finally the kinetic study of coating was carried out based on determined rate curves, which showed that the diffusion of carbon atoms in the coating layer controlled the coating process. [ABSTRACT FROM AUTHOR]

Homogenizing and normalizing heat treatments were performed on low carbon-manganese steel. Then, direct and continuous annealing heat treatments were carried out at 800°C, 770°C, 750°C and 725°C. Finally; dual phase ferrite-martensite steel was obtained. Thereafter, hardness and tensile tests were applied at ambient temperature, and impact tests for the initial sample and the dual-phase steels obtained from continuous and direct annealing heat treatment in the temperature ranges of (-67 to +70),(-70 to +60), (-70 to +29), respectively, were accomplished. The ductile-brittle transition temperature (DBTT) and the fracture modes of the samples were obtained, and the fracture surface of the steel was observed through scanning electron microscopy (SEM). The results revealed that the best mechanical properties in dual-phase steels, like impact toughness and flexibility, appear at the inter-critical temperature of 725°C for both continuous and direct annealing cycles. The (DBTT) for the specimens obtained from direct and continuous annealing and the initial sample were -49°C, -6°C, and -34°C, respectively. The dual-phase specimen achieved through the direct annealing method had better toughness and impact properties than the initial specimen or the one obtained through continuous annealing. [ABSTRACT FROM AUTHOR]

Novel Fe 46 Cr 23 Mo 14 Co 7 B 5 Si 5 and Fe 40 Cr 23 Mo 14 Co 7 P 6 B 5 Si 5 thin film metallic glasses (TFMGs) were successfully deposited using direct current magnetron sputtering process. Different microstructural evaluations were carried out including XRD, FE-SEM, EPMA, AFM, and TEM-SAED. Mechanical properties such as nano-indentation and fracture toughness tests were also performed on different substrates and under various applied forces. In addition, corrosion performance was carried out by potentiodynamic polarization, potentiostatic and electrochemical impedance spectroscopy tests. Formation of full, glassy phase was confirmed by XRD as well as TEM-SAED for both films. It was found that adding P element changed the cross-sectional growth of TFMG, decreased surface roughness and improved mechanical properties. It was also shown that the substrate type had minor influence on the fracture toughness values of TFMGs as compared to the applied force. P addition also led in an excellent corrosion resistance and significantly increase in polarization resistance, with more than 400 times as compared to the one for SS304 substrate. • Novel Fe 46 Cr 23 Mo 14 Co 7 B 5 Si 5 and Fe 40 Cr 23 Mo 14 Co 7 P 6 B 5 Si 5 TFMGs were successfully deposited using DC magnetron sputtering. • The adding P element changed the cross-sectional growth of TFMG and decreased the surface roughness. • The addition of P element led to an increase in all mechanical properties and exhibited an excellent corrosion resistance. • The substrate type had little effect on the fracture toughness values of TFMGs as compared to the applied force. [ABSTRACT FROM AUTHOR]

• Study of the wettability of an aluminum surface coated with a gold nanolayer. • Continuous-wave fiber laser ablation was performed on samples immersed in ethanol. • The laser treatment resulted in spherical micro/nanoparticles and microstructures. • The laser texturing of the surfaces results in superhydrophobicity properties. • Hydrophobicity property was better with gold coated aluminum surfaces. This paper describes the fabrication of superhydrophobic surfaces on aluminum plates coated with 15 or 40 nm gold nanolayers by a continuous-wave fiber laser ablation in ethanol. Laser ablation resulted in the creation of Al 2 O 3 microstructures combined with Au micro/nanoparticles on the Al surface. Significant structural evolutions such as reduction of micro/nanostructure size and the percentage of the oxygen concentration were observed on the surfaces by increasing the thickness of the Au nanolayer. In addition, the fabricated Au and Al 2 O 3 nanoparticles separated from the Al surface were non-spherical and roughly spherical in shapes, respectively. The static water contact angle technique to the evolution of wetting properties was employed. The laser-ablated Al sample with a 40 nm Au layer demonstrated a near superhydrophobic surface with a water contact angle of 152 ± 2°. The results of the various characterizations showed that the surface topography was the dominant factor in specifying the degree of hydrophobicity. [ABSTRACT FROM AUTHOR]

• It was a one-step method with continuous-wave fiber laser ablation on an Aluminum plate coated with gold nanolayer. • Novel Au@Al 2 O 3 core-shell nanoparticles immersed into ethanol were synthesized. • These nanoparticles had significant optical properties. Uniform oxide-layer-wrapped plasmonic nanoparticles currently widespread, demand materials in optoelectronic, photonic and catalyst applications. Laser ablation is the most common method to fabricate these materials. In this research, a prompt, eco-friendly and cost-effective method is presented to fabricate novel Au@Al 2 O 3 core-shell nanoparticles. It is a one-step method with continuous-wave fiber laser ablation on an Aluminum (Al) plate coated with gold (Au) nanolayer immersed in ethanol. The core-shell nanoparticles were characterized by transmission electron microscopy, selected area electron diffraction technique, scanning electron microscopy and X-ray diffraction analysis. The shape of the nanoparticles was roughly spherical with an average size of approximately 20 nm. Optical properties of such as absorption spectroscopy in UV/visible/IR ranges were investigated and the calculation of band gap energy of nanoparticles was performed. A combined absorption spectrum containing two significant peaks in UV/visible/IR ranges was signified. The optical band gap was 2.9 eV which is in common and excellent range of semiconductors. This study aimed to evaluate the synthesized core-shell nanoparticle properties by this approach. The fabrication mechanisms of these core-shell nanoparticles are discussed in detail in this paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sonocolloidal obtainment of SrTiO 3 nanocrystals and other perovskite materials was studied. • An efficient green room temperature sono-assisted synthesis was developed in this work. • Engineering the role of chemistry while sonication led to this obtainment. • In depth discussions and mechanisms involved in the synthesis and sonication were disclosed. Titanate-based perovskite powders are the most widely used materials for fabrication of multilayered ceramic capacitors and thus are of significant importance. They have been synthesized by two approaches including solid-state and wet chemical processing methods. Synthesis temperature, cost of preparation and quality of synthesized powders are key factors favoring the process. Here, a new ultrasound-assisted precipitation approach is introduced which is able to obtain the quality perovskite nanocrystals such as strontium titanate, barium titanate and so on at room temperature. The obtained powder products were characterized by DTA/TGA, FT-IR, XRD, SEM, EDAX and TEM. The results indicate the room temperature formation of highly pure monosized spherical nanoscale crystals which are loosely agglomerated in nature. It is tried to add the science, mechanism involved in the synthesis and its reaction pattern to the literature along with discussing the cause of low temperature obtainment of the perovskite powder products. The approach described in the current work has the capability to be a general strategy for the synthesis of perovskite materials and essential potentials for large-scale production purposes as it is facile, low temperature and cost-effective. [ABSTRACT FROM AUTHOR]

This research evaluates hydrogen permeation and its diffusion characteristics through standalone thermally sprayed coatings of AISI 316L stainless steel. The effects of various charging currents and other parameters on hydrogen diffusion coefficient were scrutinized using electrochemical hydrogen permeation tests. Hydrogen permeation through the thermally sprayed coatings displayed anomalous behavior such that a maximum pinnacle was observed in the permeation curves, attributed to heavily trapped hydrogen atoms in the delayed surface cracks. Therefore, new diffusion parameters were defined for modeling of the anomalous permeation curves. The fitted diffusion parameters were consistently identified, and hence, the model perfectly explained experimental data. The results showed that the increase in charging current caused fast activation and development of surface cracks. The measured diffusion coefficient of hydrogen in the stainless steel thermally sprayed coating was relatively high because the microstructure of the coating contained some ferritic phases and dense dendritic structure, which configure fast diffusion paths. [ABSTRACT FROM AUTHOR]

Along with other hydrogen barrier coatings, thermally sprayed coating is one of the potential barriers against hydrogen permeation. In this research, specifications of hydrogen diffusion through thermally sprayed 316L stainless steel coating over structural steel are scrutinized by different methods, including complete and partial charging and discharging tests utilizing Devanathan–Stachurski cells. Besides, various mathematical methods are applied to obtain data about the diffusion coefficient of hydrogen, in addition to the solved and trapped hydrogen contents in the coating. The analyses are supported by means of X-ray diffraction (XRD) and microstructural observations to confirm interpretations of hydrogen permeation behavior across the coating. Because of the specific microstructure of the sprayed coatings and continuous ferritic phases across the coating, which develop short pathways for hydrogen diffusion, the thermal sprayed stainless steel coating exhibits diffusion coefficient near that of ferritic steels. Furthermore, the coating contains significantly more reversible and irreversible trap concentrations than that of ferritic steels comprise. [ABSTRACT FROM AUTHOR]

Al-0.2, 0.4, and 0.8 wt% alumina composites were manufactured via powder metallurgy and hot rolling techniques successfully followed by the accumulative roll bonding (ARB) process. Microstructural characterization of the composite strips thus fabricated was carried out using optical and scanning electron microscopy. The shear punch test (SPT) and Brinell hardness measurements were used to investigate the mechanical properties of the ARB-ed samples, which revealed that alumina powder particles became more uniformly distributed with increasing number of ARB cycles. Regarding porosity, no pores could be detected among the Al and alumina particles after the fifth ARB cycle. The results also indicated that shear elongation percentage of the specimens decreased before it gradually increased with increasing number of ARB cycles while their shear strength and hardness improved. Another finding of the present study was that the shear failure surfaces of the hot rolled strips exhibited a ductile fracture with a dimple structure while those processed by the ARB technique demonstrated shear flattened surfaces. [ABSTRACT FROM AUTHOR]

The effect of lanthanum (La) on the microstructure and high temperature mechanical properties of Ti–43.5Al–4Nb–1Mo–0.1B alloy was examined by high temperature compression tests, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that the volume fraction and the mean size of dispersed oxide particles were increased with increasing La content. Besides, a small amount of La-addition was effective in improving the peak flow stress, particularly for 0.2 at.% La-added specimen, showing 14% and 44% enhancement at 900 and 1000 °C, respectively. The microstructure of hot deformed samples also indicated that small and closely spaced oxide particles had retarding effect on dynamic recrystallization. [ABSTRACT FROM AUTHOR]

The evaluation of mechanical properties, like yield and ultimate shear strengths from shear punch tests, is important when availability of material, is limited. A shear punch test setup was built, and the mechanical properties of different strips of hot rolled pure aluminum, post-rolling annealed pure aluminum, as-milled pure aluminum, and 4 wt% Al 2 O 3 were investigated. The materials were first manufactured using powder metallurgy and then processed by hot rolling procedure. Microstructures of the samples were investigated by optical and scanning electron microscopes. It was found that by increasing alumina content in the matrix, shear strength and hardness were increased; also, the percentage of shear elongation was decreased. The results, also, indicated that by applying mechanical milling on pure aluminum powders before the hot rolling process, shear strength and hardness increased more than other samples. Moreover, shear strength was increased by increasing the amount of alumina particles in composite strips. SEM observations demonstrated that the amount of flat surface in shear failure micrographs increased by increasing the amount of shear strength and hardness. [ABSTRACT FROM AUTHOR]

Magnesium aluminate spinel (MgAl 2 O 4) is considered as one of the most important spinels possessing desirable mechanical properties, with a wide range of applications at high temperatures. Powder granulation by spray freeze drying can lead to better powder flow and distribution in the mold, resulting in a specimen with high green density and strength. Accordingly, this study aimed at investigating the influential parameters on the granulation process of spinel powders via the spray freezing drying method. At first, spinel powders with various weight percents of 20, 25, 30, 35 and 50, and PVA binders with 0, 1, 2 and 8 wt% were investigated to prepare the optimal solution. Finally, the granules were sintered using the SPS method. The obtained bodies were tested by X-ray diffraction, SEM, FE-SEM, Viscosity and UV–Vis. The results showed that the optimal amount of the binder to obtain uniform granules in this process was 3%. Also, 35 wt% of solid loads represented the optimum amount for slurries, forming granules with the size range of 10–50 μm. By powder granulation, density experienced an increase of about 20%, leading to the growth of more than 15% in the in-line transmission for the IR range. [ABSTRACT FROM AUTHOR]

Hybrid composites containing Cu nanostructures (NSs), reduced graphene oxide (RGO), and polystyrene (PS) were produced for electromagnetic shielding application. First, Cu NSs including nanoparticles (NPs), nanorods (NRs), and nanowires (NWs) were prepared by a green method using eucalyptus bark extract from the reaction of copper(II) chloride in ethylene glycol (EG) at 186 °C. The FE-SEM images, XRD patterns, and Raman spectroscopy were used to characterize these NSs. The RGO/PS composite was prepared by introducing RGO to the PS matrix. The tensile test revealed that by adding 10% of RGO to the PS matrix, the tensile strength of the RGO/PS composite increased by 13.8%. The thermal properties of the RGO/PS composite indicated that with the uniform incorporation of RGO on the PS matrix, the thermal stability of the polymer composite was elevated to 350 °C and the Tg to 112 °C. Conductive polymer nanocomposites (PNCs) were prepared by adding Cu NSs to the RGO/PS composite. The results showed that these PNCs had electromagnetic interference (EMI) shielding; the shielding effectiveness of PNCs containing 10% RGO and 25% Cu NWs was 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz. The predominant mechanism of protection in the frequency range and percentages of the filler under study was of the reflection type. [Display omitted] The Cu/RGO/PS polymer NCs have the ability of shielding against the interference of electromagnetic waves; so that the shielding effectiveness in the sample of polymer NCs containing 10 wt% of RGO and 25 wt% of Cu NWs were 36.0 dB at 8.0 GHz and 29.5 dB at 12.0 GHz. • RGO & Cu NSs were prepared by a green method using eucalyptus bark extract. • Adding 10% RGO, the tensile strength of RGO/PS polymer composite increased by 13.8%. • Thermal stability and Tg of Cu/RGO/PS NCs increased to 350 and 112 °C, respectively. • Conductive polymer NCs was prepared by adding Cu NSs to RGO/PS polymer composite. • Shielding effectiveness of Cu/RGO/PS NCs were 36 dB at 8 GHz and 29.5 dB at 12.0 GHz. [ABSTRACT FROM AUTHOR]

Abstract: In this study, aluminum matrix composites (AMC) with 2, 4, 6 and 10wt% alumina were produced using powder metallurgy (PM), mechanical milling (MM) and vacuum hot pressing (VHP) techniques; then, this was followed by the hot-rolling process. During hot rolling, AMCs with 6 and 10wt% Al2O3 were fractured whereas strip composites with 2 and 4wt% Al2O3 were produced successfully. Microstructure and mechanical properties of the samples were investigated by optical and scanning electron microscopes and tensile and hardness tests, respectively. Microscopic evaluations of the hot-rolled composites showed a uniform distribution of alumina particles in the aluminum matrix. It was found that with increasing alumina content in the matrix, tensile strength (TS) and hardness increased and the percentage of elongation also decreased. Scanning electron microscope (SEM) was used to investigate aluminum/alumina interfaces and fracture surfaces of the hot rolled specimens after tensile test. SEM observations demonstrated that the failure mode in the hot-rolled Al-2wt% Al2O3 composite strips is a typical ductile fracture, while the failure mode was shear ductile fracture with more flat surfaces in Al-4wt% Al2O3 strips. [Copyright &y& Elsevier]

Abstract: Al–Ni–Cu composite was produced using accumulative roll bonding (ARB) and electroplating processes. Nickel was electroplated on copper substrate for a certain time and voltage. In this study, the microstructural evolution and mechanical properties of the Al–Ni–Cu composite during various ARB cycles were studied by optical and scanning electron microscopes, microhardness, tensile and bending tests. It was observed that at first, nickel layers and then copper layers, were necked, fractured and distributed in aluminum matrix as accumulative roll bonding cycles were increased. Finally, after 11 cycles of ARB process, a completely uniform composite was produced with a homogeneous distribution of copper and nickel particles in aluminum matrix. The results showed that by increasing the number of ARB cycles, the bending strength of produced composite was increased. Also, it was found that when the number of cycles was increased, not only elongation was increased but also the tensile strength of the composite was improved. Microhardness for different elements in different cycles was also evaluated. Finally, fracture surfaces of samples were studied, using scanning electron microscopy (SEM), to reveal the failure mechanism. [Copyright &y& Elsevier]

Abstract: In this study, the effect of coating nickel and also its different thicknesses on the bond strength of Al–Ni–Cu layers was investigated. Furthermore, the effect of reduction in thickness and post-rolling annealing on the bond strength was evaluated in order to achieve the optimum parameter in rolling Al/Cu/Ni composites. So, after preparing samples, using peeling test, we investigated the bond strength of Al–Cu strips. The results showed that coating copper with nickel reduces the bond strength of Al–Cu strips. However, by increasing the thickness of coating, the bond strength was increased, reaching the highest level compared with the strips without coating. Also, the increase in the reduction enhanced the bond strength of the layered strips. Yet, a decrease in bond strength was achieved by post-rolling annealing of the layered strips. [Copyright &y& Elsevier]

This paper explores the effects of adding rare earth elements (lanthanum or erbium) on the oxidation properties of Ti-43.5Al-4Nb-1Mo-0.1B (TNM) alloy. Isothermal oxidation tests were performed under air atmosphere at 900 and 1000 °C. Mass gain was measured in several steps during the oxidation test, and the oxidized specimens were characterized by XRD and FE-SEM. The results showed that while adding 0.1 at.% rare earth elements (REEs) reduced oxidation rate of the TNM alloy, 0.2 at.% REEs addition increased the mass gain of the alloys. The oxidation curves were fitted by a power-law equation; the results showed that the oxidation kinetic curves of all alloys obeyed parabolic growth kinetics (n = 2). Meanwhile, the activation energy of oxidation was in the range of 40-50 kCal/mol, thereby suggesting that the scale growth was controlled by mass transport in the TiO2 layer. Also, the results of the scale characterization showed that addition of REEs at low level (e.g., 0.1 at.%) could reduce diffusion rate in the scale. However, addition of the higher amounts of La or Er (e.g., 0.2 at.%) due to the lower valency (+ 3) of these elements, as compared with Ti (+ 4), could lead to the increased anion diffusion, the formation of hillocks in the scale and a rise of the oxidation rate. [ABSTRACT FROM AUTHOR]

Plasma sprayed ceramic coatings are widely used for thermal barrier coating applications. Commercially available mullite powder particles and a mixture of mechanically alloyed alumina and silica powder particles were used to deposit mullite ceramic coatings by plasma spraying. The coatings were deposited at three different substrate temperatures (room temperature, 300 °C, and 600 °C) on stainless steel substrates. Microstructure and morphology of both powder particles as well as coatings were investigated by using scanning electron microscopy. Phase formation and degree of crystallization of coatings were analyzed by x-ray diffraction. Differential thermal analysis (DTA) was used to study phase transformations in the coatings. Results indicated that the porosity level in the coatings deposited using mullite initial powder particles were lower than those deposited using the mixed initial powder particles. The degree of crystallization of the coatings deposited using the mixed powder particles was higher than that deposited using mullite powder particles at substrate temperatures of 25 and 300 °C. DTA curves of the coatings deposited using the mixed powders showed some transformation of the retained amorphous phase into mullite and alumina. The degree of crystallization of the as sprayed coatings using the mixed powder particles was significantly increased after post deposition heat treatments. The results indicated that the mechanically alloyed mixed powder can be used as initial powder particles for deposition of mullite coatings instead of using mullite powders. [ABSTRACT FROM AUTHOR]

Abstract: Radial forging conditions of ultra-high strength 32CrMoV1210 steel was investigated by using multi-pass hot compression tests. Compression continuous cooling transformation (CCCT) diagram after final deformation pass was plotted and compared with CCT diagram in order to identify the effects of deformation on transformation behavior. Comparison between these two diagrams showed that prior deformation increased martensite start temperature, M s from 45 to 85°C. The microstructural observation illustrated that application of prior deformation leads to finer lath martensite. It also showed that when deformation temperatures decreased, the grain size and its distributions became finer and inhomogeneous, respectively. [Copyright &y& Elsevier]