Elemental Powder Mixtures Research Articles

Impact of Sintering Temperature of the Mechanical Properties of a Fe20Cr20Mn20Ni20Ti10Co5V5 Medium Entropy Alloy

Medium entropy alloys (MEAs) are new emerging engineering alloys comprising four principal elements characterised by a low enthalpy of mixing and entropies of formation between 1 and 1.5 molar gas constant. They have high strength, wear, and thermal properties. MEAs have generated interest as an alternative material in the last two decades in nuclear, aerospace, and high strength engineering applications. In this research a medium entropy alloy Fe20Cr20Mn20Ni20Ti10Co5V5 with principal elements Fe, Cr, Mn, and Ni was fabricated using spark plasma sintering. Elemental powder mixture was sintered at temperatures of 870oC, 900oC and 950oC under 35 bar pressure under an inert argon atmosphere for 45 minutes using an FCT Systeme GmbH spark plasma sintering machine. After sand blasting the densities of the samples were measured before grinding, polishing, and etching for characterisation. Microstructure analysis was carried using scanning electron and optical microscopy. Microhardness was measured using Falcon 507 hardness tester, modulus using by Anton-Paar Nanoindenter and wear using Anton-Paar TRB3 Tribometer. The elements form a solid solution with presence of a hard μ phase and soft γ-phase were observed. The hardness of the alloys sintered at 870oC and 900oC were 397 and 424 Vickers respectively. The alloy sintered at 950oC showed a hardness of 674 Vickers. After annealing the hardness increased to 736 Vickers. The modulus of elasticity and creep resistance increased after heat treatment at 700oC.The other alloys showed a decrease in hardness and other properties after annealing. Unlike in steels, where annealing reduces, in this alloy annealing increased hardness at an appropriate temperature. Fe20Cr20Mn20Ni20Ti10Co5V5 MEA exhibited good thermal stability. Further work on the alloy will involve its crystallography, and feasibility for use elevated temperature energy applications such as fuel cells, turbines and wear resistant machine components.

MECHANICAL PROPERTIES OF SINTERED AL-SN-FE ALLOYS

Plastic flow under compression was studied in samples of Al-Sn-Fe alloys produced by sintering from elemental powder mixtures. Some of the sintered composites were additionally compacted at 250°C in a closed mold at a pressure of 300 MPa, and some were processed via equal-channel angular pressing using route A (ECAP-A) at the same temperature. A key structural feature of the sintered alloys is the presence of agglomerates of solid Al3Fe particles cemented with tin, formed in place of iron powder particles as a result of interaction between Al and Fe during sintering. The agglomerates have high strength but are sufficiently ductile owing to tin. They do not break during deformation and effectively suppress the propagation of localized flow bands and microcracks. In compression tests of three-phase Al-20Sn-17Al3Fe composite samples, the particle agglomerates retained their shape and moved as solid structures, while the samples showed good ductility during testing. In ECAP processing via route A, the agglomerates were pulled in the direction of material flow, which negatively affected their ductility in subsequent compression tests.

Effect of Li Doping on Cu2SnS3/n‐Si Heterojunction Solar Cells: Experiments and Simulation

AbstractCu2SnS3 (CTS) semiconductor material owns very interesting absorbing properties that allow it to be effectively utilized in many thin‐film‐based heterojunction solar cells. In this work, using the ball milling method, a mixture of pure elemental powders is used to synthesize CTS material. Homemade undoped and Li‐doped target pellets are used to form CTS‐doped and CTS‐undoped thin films. The crystallinity investigation of synthesized targets and thin films confirms the formation of CTS tetragonal phase. Compositional, morphologic, and optic studies are also made to examine the effect of Li atom incorporation on different properties of CTS thin films. These CTS thin films are also incorporated into heterojunction solar cells (Al/n‐Si/CTS/Ag and Al/n‐Si/Li0.03CTS/Ag). In addition, J–V characteristics of both CTS and Li0.03CTS solar cells are demonstrated and discussed in details. The effect of CTS thin films' thickness on the performance is studied using Solar Cell Capacitance Simulator (SCAPS‐1D) program. The results of the calculation are discussed in details and compared with the experimental results. An increase in efficiency is achieved in solar cells based on Li‐doped CTS thin films, and it is discussed in detail along with SCAPS‐1D simulation that is carried out depending on the thickness of CTS thin films.

Powder bed fusion manufacturing of beta-type titanium alloys for biomedical implant applications: A review

Thanks to many fascinating properties, such as high mechanical properties, good corrosion resistance, and excellent biocompatibility, beta-type Ti alloys are frequently employed as biomedical implants. In recent decades, rapidly developed powder bed fusion (PBF) technologies have become new methods for fabricating beta-type Ti alloys. This article reviews the recent advances and insightful perspectives on the feedstock powder characteristics (e.g., pre-alloyed powder and elemental powder mixtures), microstructure, mechanical properties, and corrosion behavior of PBF-produced beta-type Ti alloys in the forms of bulk solid parts and lattice structures. As reviewed, PBF-produced bulk beta-type Ti alloys exhibit higher strength than their conventional counterparts, accompanying with slight decrease in the maximum deformation strain. The corrosion behavior of PBF-produced bulk beta-type Ti alloys with the identical corresponding chemical compositions is related to their phase constituents in microstructure, which results from the fabrication methods or processing procedures. Additionally, PBF-produced bulk beta-type Ti alloys still have higher elastic moduli than the human bones. Hence, with the assistance of PBF technologies, lattice structures of beta-type Ti alloys with lower and controllable moduli are developed to obtain reduced their elastic moduli. For biomedical implant applications, PBF-produced lattice structures of beta-type Ti alloys with multifunctional coatings may become promising materials in the future. Nevertheless, the investigations on the PBF-produced beta-type Ti alloys for biomedical implant applications are hitherto still in the initial stage.

Al-Fe-Ni Metallic Glasses via Mechanical Alloying and Its Consolidation

In this paper, the influence of mechanical milling on the microstructural evolution and magnetic properties of Al82Fe14Ni4 alloys prepared by mechanical alloying is investigated. The elemental powder mixture was processed under argon gas at 250 rpm and 350 rpm using a planetary ball mill. The powder particles experienced severe deformation, fragmentation and mutually cold-welding during the collisions of the balls. The diffraction peaks of the Al, Fe and Ni phases gradually disappeared during the milling process, and a halo peak corresponding to the amorphous phase formed. The amorphization of powders milled at 250 rpm was slower than that of 350 rpm. These alloys achieved a fully amorphous structure after milling for 60 h. The amorphous powder alloy milled at 350 rpm exhibited higher thermal stability compared with that of an alloy milled at 250 rpm. The saturation magnetization and coercive of the milled Al82Fe14Ni4 alloy powder were decreased following the formation of a para-magnetic amorphous phase. The highest compressive strength, about 710 MPa, was obtained for the Al82Fe14Ni4 alloy sintered at 600 °C by SPS.

Selective laser melting of in-situ CoCrFeMnNi high entropy alloy: Effect of remelting

In-situ multicomponent alloying in additive layer manufacturing shows inhomogeneous elemental distribution. This study aimed to minimize this inhomogeneity in equiatomic CoCrFeMnNi high entropy alloy (HEA) produced by selective laser melting (SLM) from a mixture of elemental powder. A detailed study was undertaken regarding the effects of remelting scan strategy on microstructural and mechanical properties, melt pool geometry, and elemental distribution of CoCrFeMnNi HEA manufactured using the SLM process. The SLM sample with remelting scan strategy showed a homogeneous elemental distribution. The remelted SLM sample showed a homogeneous hardness distribution. The X-ray diffraction of the as-built and remelted SLM showed a single-phase FCC structure, typical for a HEA. Prediction and observation of melt pool depth exhibited a lower depth in the remelted SLM samples. The microstructure of the melt pools of both as-built and remelted SLM showed a fine grain morphology, typical of rapid solidification. The boundary of melt pools in the as-built SLM and the inter-space of melt pools in the remelted SLM consisted of both coarse and equiaxed/columnar dendritic grains. The present results confirmed the possibility of fabricating a homogenized CoCrFeMnNi HEA from mixed elemental powders using SLM with remelting scan strategy.

High throughput synthesis of CoCrFeNiTi high entropy alloys via directed energy deposition

Blown-powder additive manufacturing process, directed energy deposition (DED) is applicable to scale-up material development with cost-effective elemental powder mixtures. In this paper, the effectiveness of applying DED to the design and synthesis of model CoCrFeNiTi high entropy alloys (HEAs) was demonstrated. Through a careful design of composition and delicate selection of particle size and shape, three CoCrFeNiTi HEAs with different microstructures were in-situ synthesized from premixed elemental powders. Transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction were used for microstructure characterization. H3-Co 24.4 Cr 17.4 Fe 17.5 Ni 24.2 Ti 16.5 in at% (close to Co 1.5 CrFeNi 1.5 Ti) was fabricated with a soft face-centered cubic (FCC)-γ phase structure while hard intermetallic phases such as σ-FeCr, δ-NiTi 2 , and a small amount of Ni 3 Ti 2 were precipitated and uniformed distributed in the FCC matrix for H1-Co 22.2 Cr 16.1 Fe 19 Ni 21.8 Ti 20.9 and H2-Co 25.9 Cr 15 Fe 17 Ni 20.8 Ti 21.3 . With a large percent of the secondary phases, H1 exhibited a hardness value of about 853 HV 0.5 . These HEAs displayed a high oxidation resistance comparable to Inconel 625 superalloy. A detailed evaluation of the composition, microstructure, hardness, oxidation resistance, and wear resistance of these HEAs was conducted as compared with those of a reference HEA and two popular wear-resistant steels. • CoCrFeNiTi high entropy alloys were synthesized via directed energy deposition. • Compositions were controlled by elemental powders with specified size and shape. • A high oxidation resistance comparable to IN625 was obtained. • High fraction of secondary reinforcements led to hardness higher than tool steel.

Processing and Characterization of β Titanium Alloy Composite Using Power Metallurgy Approach.

The β titanium alloy matrix composite was made from a mixture of elemental metal powders, including boron carbide. During the high-temperature sintering process, in situ synthesis took place as a result of the TiB and TiC reinforcing phases formed. The identification of these phases was confirmed by X-ray diffraction and microstructural analyses. The presence of unreacted B4C particles and the surrounding reaction layers allowed for the evaluation of diffusion kinetics of alloying elements using SEM and EDS analyses. The direction of diffusion of the alloying elements in the multicomponent titanium alloy and their influence on the in situ synthesis reaction taking place were determined. In addition, the relationship between the microstructural components, strengthening phases, and hardness was also determined. It was shown that in situ reinforcement of titanium alloy produced from a mixture of elemental powders with complex chemical composition is possible under the proposed conditions. Thus, it has been demonstrated that sufficiently high temperature and adequate holding time allows one to understand the kinetics of the synthesis of the strengthening phases, which have been shown to be controlled by the concentrations of alloying elements.

In-situ alloying of a fine grained fully equiaxed Ti-based alloy via electron beam powder bed fusion additive manufacturing process

Alloy design using Additive Manufacturing (AM) methods is an interesting research area attracting the attention of researchers across the world. Formation of strong texture, columnar grains, and chemical inhomogeneity in AM-designed alloys are among the serious challenges dealt with in various research works. This paper addresses these challenges for the first time for a Ti6Al4V–7Cu alloy produced via Electron Beam Powder Bed Fusion (EB-PBF) method following an in-situ alloying approach. In this work, a mixture of Ti6Al4V and elemental Cu powders was used as the feedstock. The results showed a relatively homogenous Cu distribution in the product due to the large melt pool created during the EB-PBF process, a development indicating the method's applicability for in-situ alloying and alloy design. The prior β columnar grains were effectively converted into equiaxed grains due to a constitutionally supercooled zone created by the rejection of Cu solutes in front of the solidification front and a relatively lower thermal gradient during EB-PBF compared with other AM processes. The addition of Cu enhanced the microhardness of Ti6Al4V, which could be considered an outcome of equiaxed grain formation, solid solution strengthening mechanism, and Ti2Cu intermetallic precipitation.

Sinterability and microstructure evolution of powder metallurgy processed titanium aluminides

The objective of this study was to assess the effect of different aluminium additions in microstructure evolution and hardness of powder metallurgy processed titanium aluminides. Alloys with aluminium contents of 10, 20, 30, 40 and 45 at.-% were prepared using mixtures of elemental powders that were cold uniaxially pressed. Sintering was conducted at 1300 and 1400°C for 2 h under argon atmosphere. The results indicated a sharp decrease in sinterability for larger elemental aluminium additions. Furthermore, the hardness values decreased with the aluminium content due to the higher porosity. However, in alloys with higher aluminium content, despite the higher porosity, microstructural homogeneity was improved and equilibrium phases α2-Ti3Al and γ-TiAl could be achieved in fully lamellar Ti-40Al and Ti-45Al.

Denitrification Performance in Packed-Bed Reactors Using Novel Carbon-Sulfur-Based Composite Filters for Treatment of Synthetic Wastewater and Anaerobic Ammonia Oxidation Effluent.

To avoid nitrate pollution in water bodies, two low-cost and abundant natural organic carbon sources were added to make up the solid-phase denitrification filters. This study compared four novel solid-phase carbon-sulfur-based composite filters, and their denitrification abilities were investigated in laboratory-scale bioreactors. The filter F4 (mixture of elemental sulfur powder, shell powder, and peanut hull powder with a mass ratio of 6:2.5:1.5) achieved the highest denitrification ability, with an optimal nitrate removal rate (NRR) of 723 ± 14.2 mg NO3–-N⋅L–1⋅d–1 when the hydraulic retention time (HRT) was 1 h. The HRT considerably impacted effluent quality after coupling of anaerobic ammonium oxidation (ANAMMOX) and solid-phase-based mixotrophic denitrification process (SMDP). The concentration of suspended solids (SS) of the ANAMMOX effluent may affect the performance of the coupled system. Autotrophs and heterotrophs were abundant and co-existed in all reactors; over time, the abundance of heterotrophs decreased while that of autotrophs increased. Overall, the SMDP process showed good denitrification performance and reduced the sulfate productivity in effluent compared to the sulfur-based autotrophic denitrification (SAD) process.

Microstructure and mechanical properties of Ti–Mg lightweight heterostructured materials

To attain an unusual combination of low density and high specific strength in lightweight materials, Ti–Mg heterostructured (HS) materials comprising soft Mg domains embedded in hard Ti domain matrix were developed. Unlike hitherto reported HS materials, Ti–Mg HS materials are characterized by: (i) significant difference in coefficient of thermal expansion (CET) between soft Mg and hard Ti domains, and (ii) soft Mg domains having lower ductility. The influences of the two features on strength and ductility of HS materials remain poorly understood. To address these questions, this paper reports studies on microstructure and mechanical properties of the Ti–Mg HS materials. The Ti–Mg HS materials were prepared by spark plasma sintering of the mixture of Ti and Mg elemental powders. Ti–12Mg achieves tensile yield strength higher than that calculated using the rule-of-mixture and uniform elongation higher than that of cast Mg. Ti–15Mg obtains tensile yield strength higher than that calculated using the rule-of-mixture but uniform elongation lower than that of cast Mg. Each of Ti–20Mg and Ti–29Mg exhibits tensile yield strength lower than that calculated using the rule-of-mixture and uniform elongation lower than that of cast Mg. The mechanisms underlying strength and ductility of these Ti–Mg HS materials were revealed by analyzing the combined effects of heterogeneous deformation induced strengthening and work-hardening with stress concentration originating from the presence of cracks at Ti/Mg domain boundaries as a result of notable difference in CET between Ti and Mg.

Graded Inconel 625 coatings with in-situ processing of Ni3Al

Ni superalloys have been widely used to process coatings due to a bouquet of attractive properties in a wide range of temperature. However, higher performance Ni alloys are typically those that offer larger processing challenges. Materials systems have been studied to mitigate this challenge. In hardfacing coatings multilayers have been processed both to reduce the detrimental effects of dilution with the substrate and to enhance the resistance to crack propagation, the latter of particularly relevance when depositing alloys reinforced with hard particles with a reduced weldability but that offer enhanced performance at the surface. The present study addressed the effects of customizing a commercial Inconel 625 atomized alloy, with increasing additions of Ni and Al elemental powder mixtures, to obtain multilayered coatings with a composition and property gradient. The gradual additions of Ni + Al powder mixture to the IN 625 atomized alloy allow for the in-situ synthesis of aluminides while maintaining good weldability, increasing mechanical properties and oxidation resistance. Results show a continuous solidification microstructure, crack-free multilayer coatings with smooth chemical composition profiles and property gradient. A gradual change on the strengthening mechanisms is identified, from solid solution on the first layer of IN 625 to a mixture of solid solution and Ni3Al precipitate dispersion on the top layer processed with the feedstock richer in the Ni + Al powder mixture. These changes induced increasing elastic modulus, hardness and oxidation resistance at 1300 °C following the chemical composition gradient in coatings.

Structural and Optical Characterization of Mechanochemically Synthesized CuSbS2 Compounds.

One of the areas of research on materials for thin-film solar cells focuses on replacing In and Ga with more earth-abundant elements. In that respect, chalcostibite (CuSbS2) is being considered as a promising environmentally friendly and cost-effective photovoltaic absorber material. In the present work, single CuSbS2 phase was synthesized directly by a short-duration (2 h) mechanochemical-synthesis step starting from mixtures of elemental powders. X-ray diffraction analysis of the synthesized CuSbS2 powders revealed a good agreement with the orthorhombic chalcostibite phase, space group Pnma, and a crystallite size of 26 nm. Particle-size characterization revealed a multimodal distribution with a median diameter ranging from of 2.93 μm to 3.10 μm. The thermal stability of the synthesized CuSbS2 powders was evaluated by thermogravimetry and differential thermal analysis. No phase change was observed by heat-treating the mechanochemically synthesized powders at 350 °C for 24 h. By UV-VIS-NIR spectroscopy the optical band gap was determined to be 1.41 eV, suggesting that the mechanochemically synthesized CuSbS2 can be considered suitable to be used as absorber materials. Overall, the results show that the mechanochemical process is a viable route for the synthesis of materials for photovoltaic applications.

Mechanochemical synthesis of γ-CoTe2 nanocrystals and their application for determination of ferulic acid

The synthesis of the γ-CoTe2 nanocrystals from a mixture of elemental Co and Te powders was achieved using a ball mill's mechanical energy for only 6 h. The characterization of structure, morphology, and magnetic properties of the synthesized powders utilized X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and magnetometry. Its application as an electrochemical sensor for the determination of ferulic was investigated by cyclic voltammetry. The first 6 h of the milling time were enough to transform the starting powder mixtures, Co32Te68 and Co34Te66, in composites containing up to 86% of γ-CoTe2 nanocrystals with effective sizes of about 25 nm (volume-weighted diameter size) and 13 nm (surface-weighted 'true' crystallite size for an ellipsoidal domain shape). The explanation of the magnetometry results was based on simulations via Langevin models considering two magnetic counterparts: one superparamagnetic and other ferromagnetic (due to interacting/larger magnetic grains). The γ-CoTe2 nanocrystals modified glassy carbon electrode (γ-CoTe2/GCE) displayed outstanding sensing abilities concerning a wide linear range and one of the nethermost detection limits for ferulic acid compared to earlier reports. This excellent performance was extended to real cosmetic samples and is displayed as an alternative for quality control routines and/or real-time analysis without interfering with different components of serum lotions.

Comparison of microstructure and mechanical behavior of Ti-35Nb manufactured by laser powder bed fusion from elemental powder mixture and prealloyed powder

Although different types of powder feedstock are used for additive manufacturing via laser powder bed fusion (L-PBF), limited work has attempted to directly compare the microstructure and mechanical behavior of components manufactured from those powder feedstock. This work investigated the microstructure, phase composition, melt pool morphology, and mechanical properties of a prealloyed Ti-35Nb alloy manufactured using L-PBF and compared these to their counterparts produced from elemental powder mixture. The samples manufactured from the powder mixture are composed of randomly distributed undissolved Nb in the α/β matrix, resulting from the unstable melt pool during the melting of the powder mixture. By contrast, parts produced from prealloyed powder display a homogeneous microstructure with β and α″ phases, owing to the full melting of prealloyed powder, therefore, a more stable melt pool to achieve a homogeneous microstructure. The Ti-35Nb manufactured from prealloyed powder exhibits large tensile ductility (about 10 times that of the counterparts using mixed powder), attributed to the high homogeneity in microstructure and chemical composition, strong interface bonding, relatively low oxygen content, and the existence of a large amount of β phase. This work sheds insights into understanding the effect of powder feedstock on the melt pool stability therefore the microstructure and mechanical behavior of the resultant parts.

Corrosion Resistance of Selective Laser Melted Ti6Al4V3Cu Alloy Produced Using Pre-Alloyed and Mixed Powder.

Metallic elemental powder mixture and pre-alloyed metallic powder are both frequently used powder feedstock in the additive manufacturing process. However, little research has been conducted to compare the corrosion behavior of selective laser melting (SLM) alloys, fabricated by pre-alloyed metallic powder and mixed metallic powder. Hence, it is important to investigate the corrosion behavior of SLMed alloys, as well as the corresponding cast ingot, with the aim to better understand the feasibility of designing new materials. In this work, the SLM-produced Ti6Al4V3Cu alloys were manufactured using a metallic elemental powder mixture and pre-alloyed metallic powder, respectively. The corrosion behavior of the different Ti6Al4V3Cu alloys was investigated in following electrochemical tests and ion release measurements. The results showed that the Ti6Al4V3Cu alloy prepared by pre-alloyed metallic powder showed better corrosion resistance than that produced from mixed metallic powder. Moreover, the SLM-produced Ti6Al4V3Cu alloys performed significantly better in corrosion resistance than the cast Ti6Al4V3Cu. The results are expected to achieve a better understanding of the feasibility of designing new materials using mixed powders, contributing to reducing development costs and cycles.

Elimination of Composition Segregation in 33Al-45Cu-22Fe (at.%) Powder by Two-Stage High-Energy Mechanical Alloying.

In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al–45Cu–22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts. The alloying was conducted in two stages: at the first stage, a Cu+Fe powder mixture was ball-milled for 90 min; at the second stage, Al was added, and the milling process was continued for another 24 min. The main products of mechanical alloying formed at each stage were studied using X-ray diffraction phase analysis, Mössbauer spectroscopy, transmission electron microscopy, and energy-dispersive spectroscopy. At the end of the first stage, crystalline iron was not found. The main product of the first stage was a metastable Cu(Fe) solid solution with a face-centered cubic structure. At the second stage, the Cu(Fe) solid solution transformed to Cu(Al), several Fe-containing amorphous phases, and a spinel phase. The products of the two-stage process were different from those of the single-stage mechanical alloying of the ternary elemental powder mixture; the formation of undesirable intermediate phases was avoided, which ensured excellent composition uniformity. A sequence of solid-state reactions occurring during mechanical alloying was proposed. Mesopores and a spinel phase were the features of the two-stage milled material (both are desirable for the target catalyst).

Seynergistic effect of Mo and Zr additions on microstructure and mechanical properties of Nb‐Ti‐Si‐based alloys additively manufactured by laser directed energy deposition

• Nb-22Ti-15Si- x Mo-yZr alloys additively manufactured by laser directed energy deposition using elemental powder mixtures. • The microstructure evolution of Nb-22Ti-15Si- x Mo-yZr alloys before and after heat treatment are studied. • The crystalline orientation relationship in Nb-22Ti-15Si- x Mo-yZr alloys before and after heat treatment are investigated. • Fracture behaviors of Nb-22Ti-15Si- x Mo-yZr alloys before and after heat treatment are discuss in detail. The synergistic effect of Mo and Zr additions on microstructure evolution, room-temperature fracture toughness and microhardness of Nb-22Ti-15Si- x Mo- y Zr ( x = 4,8, y = 3,6 ) alloys manufactured by laser directed energy deposited (L-DED) have been investigated. The major phases in as-deposited 4Mo-3Zr alloy are Nb solid solution (Nbss), Nb 3 Si and γ-Nb 5 Si 3 . The Nb 3 Si phases disappear with increasing Mo content to 8 at.% or increasing Zr content to 6%. γ-Nb 5 Si 3 precipitates formed in the Nbss of as-deposited x Mo- y Zr alloys due to the cyclic re-heating, and the γ-Nb 5 Si 3 precipitates and Nbss matrix exhibits orientation relationship (OR) of [001] Nbss //[ 1 ¯ 112] γ and (110) Nbss //(01 1 ¯ 0) γ in as-deposited 4Mo-6Zr alloy. The microstructure of x Mo- y Zr alloys became relative homogeneity and the Nbss matrix showed the better continuity after the heat treatment (1400 °C/30 h). The Nb 3 Si phase has transformed into Nbss and α-Nb 5 Si 3 with the OR have been determined as {100} Nbss //{100} α and{111} Nbss //{111} α in the heat-treated 4Mo-3Zr alloy. When Mo content increase to 8at.%, a part of γ-Nb 5 Si 3 phase also transformed into the α-Nb 5 Si 3 phase with the OR have been determined as {11 2 ¯ 0} γ //{110} α and {10 1 ¯ 0} γ //{111} α after heat treatment. Among the as-deposited alloys, the 4Mo-6Zr alloy has the highest fracture toughness K Q with the lowest hardness. The average K Q of 4Mo-6Zr and 8Mo-6Zr alloys increased by 28% and 30% after the heat treatment, and reached 13.61 and 11.43 MPa·m 1/2 , respectively. The hardness of Nb-22Ti-15Si- x Mo- y Zr alloys is significantly decreased after the heat treatment.

The microstructure and compressive properties of a sintered Fe–Mn–Al porous steel produced by blended elemental powder mixture

In this study, powder compacts produced by mixed elemental Fe, Mn, Al and C powders without ball milling were sintered at 640∘C and 1200∘C, respectively. The results revealed that intermetallic phases belonging to Fe2Al5 and Al8Mn5 appeared after pre-sintered at 640∘C. When the temperature increased to 1200∘C, only α-Fe phase existed. The total porosities of the sintered samples were ∼60 vol.% at 640∘C and ∼70 vol.% at 1200∘C, and the peak compressive strength of the 1200∘C-sintered samples was ∼1.6 MPa at the strain of ∼11%.