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Tungsten and its alloys are considered to be the most nominated plasma-facing materials in fusion reactors, which will be exposed to enormously rigorous conditions such as thermal load, plasma exposure, and neutron radiation. At present, the research on the behavior of oxide particle-reinforced tungsten-based materials under long-term steady-state heat load and transient thermal shock is insufficient. The purpose of this study is to investigate the performance of yttria particle-reinforced tungsten plates prepared by the wet chemical method under heat loads by means of indirect coupling experiments. An Nd:YAG laser device is used to perform thermal shock events. The surface damage and microstructure evolution of rolled and fully recrystallized samples exposed to laser thermal shock are observed and analyzed. The cracking threshold of the rolled and fully recrystallized samples is about 0.40~0.48 GW/m2; the degree of surface damage of them aggravates with the increased laser power density. What is more, cracks or even melting damage could be observed on the surface and be accelerated by the process of recrystallization, resulting in the degradation of the ability to withstand the thermal shock of the material. [ABSTRACT FROM AUTHOR]

Based on wet chemical precipitation and spray drying technology, a Y–Zr-doped W powder was prepared as a precursor material for the preparation of Y–Zr-modified WC-8Co cemented carbides. The Y–Zr-modified WC-8Co hard alloy prepared by low pressure sintering method was used to study the change in the interface structure between the second phase and the substrate. The result showed that in the Y–Zr-doped W powder, the second phase was Y 2 O 3 and ZrO 2 particles. The Y 2 O 3 particles had a coherent interface with the W matrix, which was the reason for the formation of intragranular nano second phases in the modified hard alloys. The interface between ZrO 2 and W particles exhibited a semi coherent relationship, which was consistent with the interface structure of WC crystals and the second phase at grain boundaries. Some free second phase particles Y 2 O 3 and ZrO 2 in the doped powder formed a staggered interface structure in the modified alloy, generating Y–Zr–O solid solutions dispersed in the bonding phase. The performance of Y–Zr-modified WC-8Co hard alloy were superior to pure WC-8Co alloy prepared by the same process. The stable and compatible interface structure between WC grains and the second phase was an effective means to improve the performance of modified WC-8Co cemented carbide. [ABSTRACT FROM AUTHOR]

Investigations are conducted of the recrystallization behavior of pure tungsten through different thickness reductions by isothermal annealing at 1350 °C. Concise description is made of the recrystallization kinetics by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model in combination with hardness test results. The rate of the recrystallization process increases with the deformation ratio. For further investigations, three boundary maps of tungsten plates which are of different thickness reductions by rolling and in full recrystallization are obtained, each covering an area of 1.15 × 1.05 mm 2 on the transversal section comprising the rolling direction (RD) and the normal direction (ND). The average grain size and its distribution of pure tungsten can be easily calculated, and hence the grain aspect ratios of pure tungsten. [ABSTRACT FROM AUTHOR]

The equiatomic CoCrFeMnNi high entropy alloy, which crystallizes in the face-centered cubic (FCC) crystal structure, was prepared by the spark plasma sintering technique. Dynamic compressive tests of the CoCrFeMnNi high entropy alloy were deformed at varying strain rates ranging from 1 × 10 to 3 × 10 s using a split-Hopkinson pressure bar (SHPB) system. The dynamic yield strength of the CoCrFeMnNi high entropy alloy increases with increasing strain rate. The Zerilli-Armstrong (Z-A) plastic model was applied to model the dynamic flow behavior of the CoCrFeMnNi high entropy alloy, and the constitutive relationship was obtained. Serration behavior during plastic deformation was observed in the stress-strain curves. The mechanism for serration behavior of the alloy deformed at high strain rate is proposed. [ABSTRACT FROM AUTHOR]

Y/Zr-doped tungsten(W) powders were prepared by chemical precipitation method and spray drying technology, which was used to modify WC-8Co cemented carbides. The composition and microstructure of the Y/Zr-doped powder and alloy was characterized. The second phase referred to the elements or compounds except the matrix in the Y/Zr-doped powder or alloy. The elemental composition and interfacial structure of the second phase in alloys were discussed in detail. The improvement mechanism of the interface structure between the second phase and the matrix on the alloy properties was analyzed. The results indicated that the components of the second phase in rare earth doped hard alloys were Y 2 O 3 and ZrO 2. There was good consistency between the crystal plane of Y 2 O 3 and WC, which created a coherent interface relationship. A transitional interface structure was formed at the intersection of Y 2 O 3 particles and WC grains. Due to the good interface relationship between Y 2 O 3 and WC, as well as the transition interface structure, Y-doped WC-8Co hardmental exhibited the best performance, with hardness, fracture toughness, and transverse fracture strength(TRS) of 91.1 HRA, 13.8 MPa·m1/2, and 2730 MPa, respectively. • Introduced a new method for preparing Y/Zr-doped WC-8Co hard alloys. • A transition interface was formed between Y 2 O 3 and WC in the Y-doped WC-8Co hard alloy. • The interface was not clear between ZrO 2 and WC in the Zr-doped WC-8Co hard alloy. [ABSTRACT FROM AUTHOR]

A modified WC-8Co hard alloy was prepared using W-Y 2 O 3 powders as precursor materials. The composite powders was prepared using chemical deposition method and ball milling mixed process. The alloys was prepared using gas pressure sintering process. The microstructure of powders and alloys were characterized. Hardness, toughness and wearing behaviors were tested. The microstructure, composition and interface structure of the second phase except WC or Co in the modified alloy were analyzed. Results showed that the modified WC-8Co hard alloy had a regular grain shape and the comprehensive properties of the modified alloy was better than that of pure alloys. The second phase particles with a nano size were found inside and outside grains and their main ingredient was Y 2 O 3. Y 2 O 3 inside grains existed parallel planes with WC phases but the interface of Y 2 O 3 on the grain boundary presented a V-shaped cross structure with WC phases. The second phase Y 2 O 3 nanoparticles with intragranular and intergranular distribution increased the grain strength, refined the grain size, and exerted a pinning effect on the grain migration. Therefore, the mechanical properties of the modified hard alloy were improved, and the wear amount in the cutting experiment was reduced. • Modified WC-8Co hard alloys exhibited better wear resistance and deformation resistance. • Y 2 O 3 in a form of second-phase nanoparticles distributed inside and outside WC grains in the modified WC-8Co hardmental. • The intragranular and intergranular distribution of Y 2 O 3 had different interface relationships with WC matrix. [ABSTRACT FROM AUTHOR]

A wet-chemical method combined with spark plasma sintering was used to prepare a W-Y2O3 alloy. High-temperature tensile tests and nano-indentation microhardness tests were used to characterize the mechanical properties of the alloy. After He-ion irradiation, fuzz and He bubbles were observed on the irradiated surface. The irradiation embrittlement was reflected by the crack indentations formed during the microhardness tests. A phase transformation from α-W to γ-W was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Polycrystallization and amorphization were also observed in the irradiation damage layer. The W materials tended to exhibit lattice distortion, amorphization, polycrystallization and phase transformation under He-ion irradiation. The transformation mechanism predicted by the atomic lattice model was consistent with the available experimental observations. These findings clarify the mechanism of the structural transition of W under ion irradiation and provide a clue for identifying materials with greater irradiation resistance. [ABSTRACT FROM AUTHOR]

W–ZrC composites reinforced with Sc 2 O 3 particles were produced by mechanical milling and subsequent spark plasma sintering. W–ZrC/Sc 2 O 3 composites were exposed to the He ion for 2 h with 50 and 80 eV ion energies and a particle flux of above 10 22  m −2  s −1 performed in a Large-power Materials Irradiation Experiment System (LP-MIES). Results showed that W, Sc 2 O 3 , and ZrC can combine well with one another to form a solid solution. Small amounts of ZrC particles can effectively capture impurity O in tungsten GBs and form nano-sized ZrO 2 particles. After a large He + ion irradiation, serious radiation damage occurred on the sample surfaces, exhibiting “fuzz” structures. With the increasing in He + ion energy from 50 eV to 80 eV, the microhardness of the irradiated regions rose, and pores were formed on the affected area. Besides, agglomerated second-phase groups (primary ZrC with slight Sc 2 O 3 ) tended to distribute outward. [ABSTRACT FROM AUTHOR]

In this study, a large-power inductively coupled plasma source was designed to perform the continuous helium ion irradiations of W–Cr binary alloy (W–20 wt%Cr) under relevant conditions of the International Thermonuclear Experimental Reactor. Surface damages and microstructures of irradiated W–20Cr were observed by using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The addition of Cr dramatically enhanced the micro-hardness of the obtained bulk materials, and the interface between the W matrix and the second phase Cr–O is a semi-coherent interface. After irradiation, the doping of Cr element effectively reduces the damage of the W matrix during the irradiation process. The semi-coherent interface between the second phase and the W matrix improves the anti-irradiation performance of the W–20Cr alloy. [ABSTRACT FROM AUTHOR]

The thermal stability of an yttria dispersion-strengthened tungsten plate warm-rolled to 50% thickness reduction is investigated. Isothermal annealing experiments were conducted at four temperatures and the microstructure and texture evolution were analyzed with Transmission Electron Microscopy (TEM) and Electron Backscatter Diffraction (EBSD) to understand the restoration mechanisms in the W-2 vol% Y 2 O 3 alloy. At 1200 °C, dominantly recovery occurred in the warm-rolled plate up to the longest annealing time of 84 h, whereas at temperatures of 1250 °C and above recrystallization was the dominant restoration mechanism. Microstructure and texture evolution during recrystallization were quantified in terms of grain size, aspect ratio and volume fractions of fiber texture components. The analysis reveals that the Y 2 O 3 particles play a key role in the recrystallization mechanism of the plate affecting both, nucleation and growth behavior. Their dominating effect originates from pinning of high angle boundaries causing no-convex grain shapes as well as slower recrystallization kinetics than pure tungsten, thereby improving the thermal stability of the oxide dispersion-strengthened material. [Display omitted] • Yttria dispersion-strengthened tungsten is characterized after annealing by EBSD. • Recrystallization governs restoration at 1250 °C and above, recovery at 1200 °C. • Particle-stimulated nucleation is revealed near large yttria particles. • Fine yttria particles pin boundaries causing non-convex recrystallized grains. • Zener pining improves thermal stability compared to warm-rolled pure tungsten. [ABSTRACT FROM AUTHOR]

• The effect of deformed microstructure on the recrystallization behaviors of three pure tungsten plate was studied. • The largest rolling thickness reduction ratio does not improve the mechanical properties so much during high-temperature rolling but accelerates dynamic recrystallization and subsequent static recrystallization. • Annealing of three pure tungsten plates caused fast discontinuous recrystallization followed by slower grain growth. • The rolling texture and the recrystallization texture were both strengthened with the increase of the rolling thickness reduction ratio. The annealing behaviors of three rolled pure tungsten plates with different thicknesses reduction ratios were investigated by hardness degradation during isothermal annealing at 1250 °C. The microstructures and textures of three rolled pure tungsten plates in the as-received and fully recrystallized states were characterized by Electron Backscatter Diffraction (EBSD). The stored energies of the plates in the as-received state were calculated through the specific surface density of high angle boundaries and low angle boundaries. All three plates undergo recrystallization and grain growth without an obvious recovery stage during the annealing process at 1250 °C. The recrystallization rate increases with the increased rolling thickness reduction ratios, which can be reasonably explained as the initial microstructure of the tungsten plate with the large rolling thickness reduction ratio has more dynamic recrystallization nuclei/grains and higher stored energy. The rolled and the recrystallized texture were both strengthened with the increased thickness reduction ratios, and the rolled texture is more random than the recrystallized one. [ABSTRACT FROM AUTHOR]

This paper introduced a new way to prepare WC-8Co cemented carbide doped with rare earth oxide that Y 2 O 3 /ZrO 2 was doped into powders by the wet chemical method and the alloys were densified by hot-pressing sintering. The microstructure of the powders and alloys was characterized by scanning electron microscopy and transmission electron microscopy whereas phase composition was analyzed by X-ray diffraction and energy-dispersive spectroscopy. The density, hardness, and transverse rupture strength (TRS) of the alloys were also tested. Results showed that the addition of Y 2 O 3 /ZrO 2 refined the WC grains and reaction between Y 2 O 3 and ZrO 2 generated new second phase particle of Y 4 Zr 3 O 12 in the alloy with co-doping of Y 2 O 3 and ZrO 2. The carbon content affected the porosity of WC-8Co-Y 2 O 3 /ZrO 2 , and the number of pores reduced with the increase in carbon content. Moreover, the carbon-deficient phase was generated at a low carbon content. When the carbon content was 6.15 wt%, the WC-8Co-Y 2 O 3 /ZrO 2 alloys achieved the best comprehensive properties. • WC-8Co cemented carbides doped with Y 2 O 3 /ZrO 2 was prepared by a new method. • The addition of Y 2 O 3 /ZrO 2 inhibited the growth of WC grains and improved properties of WC-8Co cemented carbides. • The carbon content played a significant role on the toughness of WC-8Co-Y 2 O 3 /ZrO 2 cemented carbides. [ABSTRACT FROM AUTHOR]

WC-8Co composite powders doped with Y 2 O 3 were prepared by wet chemical method, and the densification of alloy proceeded by spark plasma sintering at 1200 °C, 1250 °C, and 1300 °C. The microstructure of the composite powders and alloys was analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. Result showed that the addition of Y 2 O 3 could refine WC particles during carbonization and WC grains during sintering. In the microstructure of WC-Co alloys, Y 2 O 3 solidly dissolved in the body of WC crystal with the form of the second-phase nanocrystal. Moreover, the effect of sintering temperature on WC-8Co cemented carbide doped with Y 2 O 3 was studied. The comprehensive performance of WC-8Co cemented carbide doped with Y 2 O 3 was best at the sintering temperature of 1250 °C with the hardness of 19.64 GPa and fracture toughness of 11.97 MPa m1/2. • WC-8Co-0.5Y 2 O 3 cemented carbides were prepared by wet chemical method and SPS technology. • > Y 2 O 3 refined the particle size of WC during carbonization and retained the grain growth of WC during sintering. • > The addition of Y 2 O 3 improved properties of WC-8Co cemented carbides. [ABSTRACT FROM AUTHOR]

• Microstructural evolution during annealing of pure tungsten warm-rolled by 67%. • ESBD reveals fast discontinuous recrystallization followed by slower grain growth. • Recrystallization sharpens grain size distribution, scaling during grain growth. • Recrystallized grains keep aspect ratio, deformed grains show transient increase. • Texture strength increases during recrystallization, decreases during grain growth. The mechanical behavior, microstructure and texture evolution were investigated during isothermal annealing at 1300 °C of pure tungsten moderately warm-rolled to 67% thickness reduction. The degradation of the mechanical properties is characterized by hardness testing. The microstructure and texture evolution during heat treatment were characterized by Electron Backscatter Diffraction. During annealing of the moderately warm-rolled tungsten, recrystallization occurred first, quickly followed by relatively slow grain growth. The recrystallized volume fractions determined from hardness measurements and microstructural characterization were essentially the same. The evolution of the grain sizes during recrystallization was analyzed independently for deformed and recrystallized grains. Quantitative texture analysis showed that the overall texture strength is enhanced after recrystallization. As recrystallization strongly affects the mechanical properties of tungsten, such insights in the annealing behavior of warm-rolled tungsten plates are valuable for an understanding of their performance as potential plasma-facing materials in future fusion reactors. [ABSTRACT FROM AUTHOR]

W-2vol.%TiC composites were prepared through wet-chemical method combined with sintering and hot-rolling process. In this work, the evolution of damage micrograph in W-2vol.%TiC was studied by SEM in situ observation as functions of annealing temperature and implantation fluence. The results show that the surface morphology of the W matrix was slightly affected after D ions irradiation, while the dispersively distributed TiC particles were damaged severely. After annealing at 1173 K and 1573 K, the irradiation damage structure was repaired. [ABSTRACT FROM AUTHOR]

Highlights • Large-sized W-Y 2 O 3 bulk material was successfully produced. • Rolling deformation induced anisotropic microstructure and fiber geometric structure. • Thermal conductivity has a linear relationship with reciprocal temperature. Abstract Tungsten (W) or W alloys are the main candidates for plasma-facing materials of future fusion reactors. Large-sized W-Y 2 O 3 bulk material has been successfully produced in this study for future engineering applications. Wet chemical method and continuous hydrogen (H 2) reduction were applied to achieve mass preparation of W-Y 2 O 3 composite powder. The final bulk material was obtained using the H 2 atmosphere sintering technique and rolling deformation process. Conventional X-ray diffraction patterns were used to characterize the different surfaces of the rolled specimen, which coincide with the results of electron backscatter diffraction detection, to evaluate the texture information. The 50% rolled W-Y 2 O 3 bulk material have three types of textures, namely, θ-fiber, α-fiber, and γ-fiber. Notably, the thermal conductivity exhibits no obvious difference between sintered bulk at the original state and rolled bulk along various directions. After rolling deformation of the W-Y 2 O 3 bulk material, the effect of the anisotropic microstructure on the thermal conductivity can be offset by the effect of the fiber geometric structure. For the body-centered cubic structure of W, the thermal conductivity versus the crystal orientation should be λ [100] > λ [110]. [ABSTRACT FROM AUTHOR]

Abstract Tungsten is one of the most promising candidates for plasma-facing material for fusion. In this experiment, W–TiC–Y 2 O 3 composites were successfully prepared by the wet chemical method. The properties of the W–TiC–Y 2 O 3 composites were studied through field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction analysis, thermal conductivity, and transient laser thermal shock. During the sintering of the composite powder, TiC and Y 2 O 3 precipitations converted to Y-Ti-O precipitations. After transient laser thermal shock, the composites underwent melting, cracking, and resolidification, resulting in changes in surface morphology and internal structure of the composites. Graphical abstract Image 1 Highlights • W–TiC–Y 2 O 3 composites possessed excellent mechanical property and thermal shock resistance. • Y 2 TiO 5 , Y 2 TiO 6 , and Y 2 TiO 7 improved the mechanical properties of the material at high temperature. • The effect of different power density on material surface was analyzed. • The change of surface morphologies and internal structure due to transient thermal shock were discussed. [ABSTRACT FROM AUTHOR]

The mechano-chemical and wet-chemical methods were applied to prepare W-12 vol% TiC-4vol% Y 2 O 3 (hereinafter referred to as W–TiC–Y 2 O 3 ) precursors that were restored under 800 °C of hydrogen for 1 h, and the composite powders were sintered under different sintering technologies after being restored. Finally, the sintering bodies prepared through the two technologies were subjected to laser thermal impact and deuterium–ion irradiation tests. According to the tests, the W–TiC–Y 2 O 3 composite powders prepared using the mechano-chemical method displayed better dispersity, whereas the W–TiC–Y 2 O 3 sintering bodies prepared using the mechano-chemical method displayed higher density, smaller grains, higher hardness, and a more uniform distribution of the second phase and generated a more stable oxide Y 2 (Ti 2 O 7 ) and solid solution (W,Ti)C 1 -x. Moreover, the W–TiC–Y 2 O 3 composite material prepared by the mechano-chemical method displayed better thermal shock resistance and anti-irradiation performance. [ABSTRACT FROM AUTHOR]

W–3Lu 2 O 3 composites were prepared by mechanical milling and spark plasma sintering. The obtained composites were subjected to He + irradiation experiments. The irradiated samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and measurement of Vickers hardness. Thermal desorption spectroscopy analysis was performed to analyze the samples at different damage levels after Fe 2+ and D + irradiation. Results showed varied degrees of He + damage under different energies. Fuzz structures were observed on the surface of the material after irradiation. TEM results indicated that the existence of these fuzz structures was related to the formation of He bubbles. Amorphous, polycrystalline, and γ-W phases formed in areas where He bubbles existed. The measured Vickers hardness proved that radiation hardening occurred after irradiation. After Fe 2+ irradiation at different damage levels, the total retained deuterium amount of W–3Lu 2 O 3 and pure W differed, and the impact of Fe 2+ radiation for deuterium retention on pure tungsten was greater. [ABSTRACT FROM AUTHOR]

Mechanical alloying was performed in a planetary ball mill by using a rotational speed of 400 r/min and a ball to powder ratio of 20:1 at room temperature. Milling was performed for 5, 15, 25, 36, and 45 h. The effect of milling time on the microstructure and properties of alloy powders, microstructure of W–Nb alloys, and second-phase distribution were studied through field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction analyses. Results showed that crystalline size, lattice strain, and dislocation density significantly changed when the milling time was increased from 5 h to 25 h. Further increase in the milling time slightly influenced the parameters. W–Nb alloy powders exhibited the lowest lattice parameters after 25 h of milling. Among the formed W–Nb solid solutions, W–Nb alloy milled for 25 h exhibited the lowest porosity and contained homogenously and finely distributed Nb-rich phases in the tungsten grains and boundaries. Thermal desorption spectroscopy analysis was also performed to assess deuterium retention after irradiation. Based on the total amount of deuterium in the W–Nb alloys, those milled for 25 h exhibited the optimal irradiation resistance. In conclusion, 25 h is the optimal milling time for mechanical manufacture of W–Nb alloys. [ABSTRACT FROM AUTHOR]

W–15 wt.% Ti alloys were fabricated through mechanical alloying with different milling times ranging from 10 h to 80 h. The powders milled for 10, 30, 60, and 80 h were sintered by spark plasma sintering at 1600 °C. The milled powders and sintered samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; and their microhardness and thermal conductivity were investigated. Results revealed that the particles underwent welding, fracturing, and rewelding when the milling time increased. The grain size decreased, whereas the microstrain increased from 0.344% at 10 h to 0.543% at 80 h and dislocation density increased with the increase in milling time. However, the WC contamination was induced into the powder after a long milling time, thereby possibly forming the (Ti,W)C 1 − x solid solution with the addition of Ti after sintering. The second phase became uniformly distributed and the W grain size was reduced from 1.48 μm to 0.31 μm after a long milling time. Furthermore, the Vickers hardness increased from 543.05 Hv to 890.30 Hv and thermal conductivity also increased with an increase in milling time. [ABSTRACT FROM AUTHOR]

“Pure” W was prepared through a powder metallurgy route by using hard alloy (WC–Co) milling tank and balls to mill WO 3 powder, reducing with high purity H 2 , and sintering with spark plasma sintering technique. XRD, SEM, and TEM were used to characterize the phase and phase structures. Results showed that the cobalt tungsten carbide (Co 3 W 10 C 3.4 ) phase was induced from the milling tank and balls. After the “pure” W bulk was exposed to helium ions for 2 h, the cobalt tungsten carbide phase was found to be surrounded by the lattice distortion phase of W, which showed high irradiation resistance. [ABSTRACT FROM AUTHOR]

W–30Cu/(0, 0.25, 0.5, 1, and 2) wt.% TiN composites were prepared via electroless plating with simplified pretreatment and powder metallurgy. The phase and morphology of W–Cu/TiN composite powders and sintered W–Cu/TiN samples were characterized via X-ray diffraction and field emission scanning electron microscopy. Transmission electron microscopy was performed to characterize the microstructure of the sintered W–Cu/TiN samples. The relative density, hardness, electrical conductivity, and compressive strength of the sintered samples were examined. Results showed that W–30Cu composite powders with a uniform structure can be obtained using W powder pretreated with nitric acid, ammonium fluoride, and hydrofluoric acid followed by electroless Cu plating. The addition of TiN nanoparticles significantly affected the microstructure and properties of the W–30Cu composites. A good combination of the compressive strength and hardness of the W–30Cu composite material can be obtained by incorporating the TiN additive at 0.25 wt.%. However, the relative density and electrical conductivity slightly decreased. [ABSTRACT FROM AUTHOR]

W–1 wt%Nb/TiC composites were prepared by mechanical milling and spark plasma sintering. Field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and thermal conductivity analyses were used to characterize the samples. Results showed that niobium carbide (NbC) formed in the composites. The relative density of the composites has been improved after adding Nb into W–1 wt%TiC. The tensile strength increased as well because Nb has high affinity for impurities such as O, C, and N and can form with these elements hard compounds. The thermal conductivity of W–1 wt%Nb/TiC was also improved, in comparison with that of W–1 wt%TiC. [ABSTRACT FROM AUTHOR]

Pure tungsten and W–3 wt.% Lu 2 O 3 samples were fabricated by spark plasma sintering at 1600 °C for 3 min from 4 h ball–milled powders. These samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and energy-dispersive spectroscopy, Vickers microhardness, and thermal conductivity analyses. Results revealed that doped Lu 2 O 3 particles influenced the densifying and strengthening of W–3 wt.% Lu 2 O 3 composite compared with pure tungsten. The relative density and microhardness of pure tungsten were 93.49% and 446.4 Hv, and those for W–3 wt.% Lu 2 O 3 samples were 96.21% and 551.7 Hv, respectively. [ABSTRACT FROM AUTHOR]

W–1 wt% Sm 2 O 3 powders doped with highly uniform Sm 2 O 3 were successfully synthesized by a novel wet chemical method followed by hydrogen reduction. The powders were consolidated by spark plasma sintering (SPS) at 1800 °C to suppress grain growth during sintering. The FE-SEM and HRTEM analysis, tensile test and thermal conductivity measurements were used to characterize these samples. The grain size, relative density of the bulk samples fabricated by SPS sintering were 4 μm and 97.8%, respectively. The tensile strength values of Sm 2 O 3 /W samples were higher than those of pure W samples. As the temperature rises from 25 to 800 °C, the thermal conductivity of pure W and W–1 wt% Sm 2 O 3 composites decreased with the same trend and the thermal conductivity of both samples was above 160 W/m K at room temperature. [ABSTRACT FROM AUTHOR]

Powder metallurgy technique was employed to prepare W–30wt.% Cu composite through a chemical procedure. This includes powder pre-treatment followed by deposition of electroless Cu plating on the surface of the pre-treated W powder. The composite powder and W–30Cu composite were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Cold compaction was carried out under pressures ranging from 200MPa to 600MPa while sintering at 850°C, 1000°C and 1200°C. The relative density, hardness, compressive strength, and electrical conductivity of the sintered samples were investigated. The results show that the relative sintered density of the titled composites increased with the sintering temperature. However, in solid sintering, the relative density increased with pressure. At 1200°C and 400MPa, the liquid-sintered specimen exhibited optimum performance, with the relative density reaching as high as 95.04% and superior electrical conductivity of IACS 53.24%, which doubles the national average of 26.77%. The FE-SEM microstructure evaluation of the sintered compacts showed homogenous dispersion of Cu and W and a Cu network all over the structure. [ABSTRACT FROM AUTHOR]

• A W–0.4wt% Y 2 (Zr)O 3 alloy with high recrystallization temperature and superior tensile strength have been prepared. • The strength and elongation of the RD and TD orientation samples of the WYZ alloy depend on the length of the free dislocation slip path and the capacity of grains to dislocations. • With the increase of tensile temperature, the α- and γ-fiber texture on the fracture side surface were significantly enhanced. • Larger tensile strain rates overestimate DBTT but exhibit high tensile strength at temperatures above DBTT. A W–0.4wt% Y 2 (Zr)O 3 (WYZ) alloy plate with superior mechanical properties and improved high-temperature stability was prepared by hot rolling. The tensile properties of WYZ alloys with different orientations and recrystallization states were investigated at a temperature range from room temperature (RT) to 500°C. The texture intensity of the original WYZ alloy was weak, but it was significantly enhanced after annealing. The initial recrystallization temperature of the WYZ alloy was approximately 1400°C. After recrystallization annealing, the strength of the WYZ alloy decreased significantly, but it showed an increased ductility. The ultimate tensile strength and fracture elongation of the samples along the rolling direction (RD) were always significantly higher than those of the samples along the transverse direction (TD). Orientation and annealing had no evident effect on ductile-to-brittle transition temperature (DBTT) from tensile data, but increasing strain rate would overestimate DBTT. The DBTT of the WYZ alloy from tensile data was approximately between 200°C and 300°C. With the increase in tensile test temperature, the strengths of α- and γ-fiber textures on the side of fracture surface increased significantly. The increase in α- and γ-fiber texture contents was beneficial to ductility enhancement in the WYZ plate. [ABSTRACT FROM AUTHOR]

The addition of carbon can improve high temperature creep resistance of TiAl intermetallics. In this work, the precipitation behavior of Ti-45Al-3Fe-2Mo-0.5C during the creep process at 750 °C and 200 MPa has been investigated. The results show that the strain of C-doped TiAl is about 60% lower than that of the C-free TiAl at a creep time of 8 × 105 s. The precipitations, including β phase, Ti 3 AlC phase and Ti 2 AlC phases, occurred in the lamellar structure of Ti-45Al-3Fe-2Mo-0.5C after creep tests. The formation of both Ti 3 AlC and Ti 2 AlC carbides is promoted at dislocations during creep tests. • The addition of carbon can improve high temperature creep resistance of TiAl intermetallics. • The β phase, Ti 3 AlC phases and Ti 2 AlC phases can precipitate in the lamellar structure during the creep process. • The dislocation movement during the creep process in the γ phase can promote the precipitation of Ti 3 AlC and Ti 2 AlC phases. [ABSTRACT FROM AUTHOR]