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High-performance refractory alloys with ultrahigh strength and ductility are in demand for a wide range of critical applications, such as plasma-facing components. However, it remains challenging to increase the strength of these alloys without seriously compromising their tensile ductility. Here, we put forward a strategy to “defeat” this trade-off in tungsten refractory high-entropy alloys by stepwise controllable coherent nanoprecipitations (SCCPs). The coherent interfaces of SCCPs facilitate the dislocation transmission and relieve the stress concentrations that can lead to premature crack initiation. As a consequence, our alloy displays an ultrahigh strength of 2.15 GPa with a tensile ductility of 15% at ambient temperature, with a high yield strength of 1.05 GPa at 800 °C. The SCCPs design concept may afford a means to develop a wide range of ultrahigh-strength metallic materials by providing a pathway for alloy design. Tungsten-based alloys with ultrahigh strength and ductility are in high demand for a wide range of applications, potentially for fusion reactors. Here the authors develop a tungsten refractory high-entropy alloy with high strength (~2.15 GPa) and sufficient ductility (~15%).

Operating fuel cells in alkaline environments permits the use of platinum-group-metal-free (PGM-free) catalysts and inexpensive bipolar plates, leading to significant cost reduction. Of the PGM-free catalysts explored, however, only a few nickel-based materials are active for catalyzing the hydrogen oxidation reaction (HOR) in alkali; moreover, these catalysts deactivate rapidly at high anode potentials owing to nickel hydroxide formation. Here we describe that a nickel–tungsten–copper (Ni 5.2 WCu 2.2 ) ternary alloy showing HOR activity rivals Pt/C benchmark in alkaline electrolyte. Importantly, we achieved a high anode potential up to 0.3 V versus reversible hydrogen electrode on this catalyst with good operational stability over 20 h. The catalyst also displays excellent CO-tolerant ability that Pt/C catalyst lacks. Experimental and theoretical studies uncover that nickel, tungsten, and copper play in synergy to create a favorable alloying surface for optimized hydrogen and hydroxyl bindings, as well as for the improved oxidation resistance, which result in the HOR enhancement. The lack of efficient and cost-effective catalysts for H 2 oxidation reaction (HOR) hinders the application of anion exchange membrane fuel cells. Here, authors report a ternary nickel-tungsten-copper nanoalloy with marked HOR activity and stability that rivals the benchmark platinum catalyst.

With the rapid development of integrated circuit technology, the performance requirements of thin film materials are becoming more and more stringent, and refractory metal alloy targets show greater application value, especially tungsten alloy and molybdenum alloy sputtering targets as a typical representative. This paper focuses on tungsten alloy and molybdenum alloy targets, presenting the latest applications of these alloy targets in large-scale integrated circuits. It further analyzes the correlation between sputtering target performance and deposited film quality. Finally, it reviews the progress in preparing refractory metal alloy targets and outlines future prospects.

Based on Euler-Lagrange element coupling (CEL) simulation algorithm, this paper uses ABAQUS software to simulate and analyze the fragmentation of warhead under single point initiation, two-point initiation and four-point initiation. Simulation results show that the prefabricated fragment of the warhead can cover the target in the axial region completely. Regarding the velocity characteristics of the head fragments, tungsten-zirconium alloy and tungsten alloy fragments show different average velocities under different initiation modes. At four point initiation, the average velocity of tungsten-zirconium alloy fragments is 1371m/s, and the average velocity of tungsten alloy fragments is 1366m/s. At two point initiation, the average velocity of tungsten zirconium alloy fragment is 1351m/s, while the average velocity of tungsten alloy fragment is 1344m/s. When the single point initiation, the average speed of tungsten-zirconium alloy fragments is 1329m/s, and the average speed of tungsten alloy fragments is 1330m/s. The four-point initiation mode shows the highest axial fragment velocity, up to 1,848 m/s, while the single-point initiation mode has a maximum velocity of 1691m/s, a difference of about 150m/s. Secondly, with the increase of the flying angle, the fragment velocity will decrease accordingly. It can be seen that in the case of four-point initiation, the speed of the axial reinforcement fragment can be greatly increased, which can better solve the problem of the central blind area caused by the traditional killing warhead when striking the target, and achieve the coverage of the entire damage target area under the static explosion condition.

The surface quality of tungsten heavy alloy parts has an important influence on its service performance. The accurate on-line prediction of surface roughness in ultra-precision cutting of tungsten heavy alloy has always been the difficulty of research. In this paper, the ultrasonic elliptical vibration cutting technology is used for ultra-precision machining of tungsten heavy alloy. Based on the idea of deep learning, the surface roughness is discretized, and the fitting problem in surface roughness is transformed into a classification problem. The generalization ability of the prediction model is improved by introducing batch standardization and Dropout. The relationship between the vibration signal and the surface roughness is established. Experimental results show that the model can achieve on-line prediction of cutting surface roughness. The prediction accuracy rate can be improved by more than 10% compared with the direct fitting method.

Tungsten is a refractory metal that has a wide range of applications in many fields. However, its high ductile-to-brittle transition temperature limits its processing and machining. While additive manufacturing is an emerging tool for manufacturing complex tungsten parts, cracking and low densification are the main challenges with printing W samples. Studies have been done using different additive manufacturing processes to fabricate high dense free of crack samples, without much success. To address this important challenge, extensive efforts have been made to investigate the effect of different processing conditions—such as laser/electron beam power, scanning speed, hatch spacing, and substrate preheating temperature—on the quality of the print. In this contribution, the most recent and relevant literature on the additive manufacturing of W and W-based alloys is reviewed. The literature is critically assessed in order to systematically investigate and report on the effect of different processing parameters on the morphology, densification, and mechanical properties of the additively manufactured W and W-based alloy parts.

The present article deals with effect of Cr addition (10 at.%) on the partitioning behavior and the consequent effect on mechanical properties for tungsten-free γ–γ′ cobalt-based superalloys with base alloy compositions of Co–30Ni–10Al–5Mo–2Ta (2Ta) and Co–30Ni–10Al–5Mo–2Ta–2Ti (2Ta2Ti). Cr addition leads to a change in the morphology of the strengthening cuboidal-shaped γ′ precipitates to a spherical shape. The site preference of Cr atoms in two alloy systems (with and without Ti) has been experimentally investigated using atom probe tomography with the supportive prediction from first principles DFT-based computations. Cr partitions more to the γ matrix relative to γ′. However, Cr also has a strong effect on the Ta and Mo partitioning coefficient across γ/γ′ interfaces. The value of partition coefficient for Mo ( K Mo ) becomes <1 with Cr addition to the alloys. Results from ab initio calculations show that the Cr atoms prefer to replace Mo atoms in the sublattice sites of the L1 2 unit cell. The solvus temperature of about 1038 and 1078 °C was measured for 10Cr2Ta and 10Cr2Ta2Ti alloy, respectively, and these Cr-containing alloys have very low densities in the range of ~8.4–8.5 gm/cm −3 . The 0.2% compressive proof strength of 10Cr2Ta2Ti alloy yields a value of 720 MPa at 870 °C, substantially better than most Co–Al–W-based alloys and many of the nickel-based superalloys (e.g., MAR-M-247).

In order to reveal the detonation effect and mechanism of covered explosive under fragment impact, based on one-dimensional shock wave theory, a theoretical model of fragment impact detonation of covered explosive is established. Combined with numerical simulation, the influence of key parameters such as fragment material, fragment shape and charge shell thickness on the detonation threshold velocity and the influence of fragment velocity on the detonation time and depth of covered explosive are obtained, and the mechanism of fragment on the detonation effect of covered explosive is revealed. The results show that the shock initiation effect of tungsten alloy fragments is better than that of 45# steel fragments. The shock initiation effect of cubic fragments is better than that of spherical fragments. When the thickness of charge shell is thin, it is the impact detonation mechanism. When the charge shell is thick, the impact detonation mechanism and the shear detonation mechanism coexist. The detonation time and detonation depth of explosives decrease with the increase of velocity, and the detonation time is proportional to the detonation depth.

Prefabricated fragment bomb will produce a large number of tungsten alloy spherical damage elements, causing damage to a wide range of targets. The phenomenon of bouncing projectile will deviate from the trajectory of fragments and affect the damage field of explosive projectile. In order to accurately obtain the influence of bouncing projectile on the residual damage of tungsten ball fragments, the damage of concrete targets caused by bouncing projectile is analyzed. The oblique penetration of tungsten ball fragments into concrete at different angles and speeds is simulated. Through the angle-by-angle approximation of cylinders and planes with different curvature radii at 1000m/s, the critical bounce angles in each case are obtained. Based on this, the critical bounce angle of each cylinder under medium and high speed conditions is obtained. The simulation results show that the critical bounce angle decreases with the increase of curvature, and the critical angle increases with the increase of velocity. The residual velocity angle of the projectile increases with the increase of curvature. The relationship between concrete damage degree and curvature and velocity is obtained. Based on the critical angle of penetration of concrete with different fragment flight parameters, the killing range of fragments can be corrected, and the accurate evaluation of the killing ability under the condition of bouncing projectile can be realized.

Long rod projectile has strong penetration capability due to its high specific kinetic energy, however there exists a limit value to improve its penetration depth by increasing the aspect ratio. A higher penetration efficiency can be obtained by equal-mass segmented rod under certain conditions. Numerical simulation study of tungsten alloy segmented rod penetrating semi-infinite steel target with the speed of 1000m/s-3000m/s was carried out. Penetration process of segmented rods were analysed and compared with the equal-mass long rods. The penetration capability of segmented rods with different number of segments and different speeds on the semi-infinite steel target was studied, and the penetration mechanism was analysed. The numerical simulation results of the ideal segmented rod penetration on thick targets can provide a reference for its practical application.