Fabrication And Properties Of Hafnium Carbide Dispersion Strengthened Tungsten Based Alloys

Fusion energy is regarded as one of the fundamental ways to solve the energy problem thoroughly.Tungsten base alloy has the advantages of high melting temperature,high strength,high thermal conductivity,high sputtering resistance and low tritium retention,which makes tungsten become the most promising material used in future reactor components.However,some disadvantages of tungsten material limit its application in the reactor,such as room temperature brittleness,recrystallization brittleness,low strength at high temperature and irradiation brittleness.In order to improve these shortcomings of tungsten materials and better apply them to the fusion reactor,a high performance WHC05 alloy was prepared by powder metallurgy combined with the method of regulating grain boundary structure and stabilizing microstructure.The application of sample seismic properties is tested.First of all,Due to the special heating mode of the spark plasma sintering device and the small size of the sintered samples,the sample can be quickly heated to a high temperature and loaded with a large pressure at the same time.Therefore,it is possible to prepare high-density fine-grained tungsten material in a short time.Therefore,we used SPS sintering method to prepare high-density W-HfC samples to optimize the components.It was found that when the addition amount of HfC reached 0.5wt.%,the tungsten alloy had the best performance.The tensile strength of WHC05 sample at 500? was 442 MPa and the elongation was 21.9%.Compared with pure tungsten,the plastic deformation occurred at 700?,indicating that the addition of HfC reduced the ductile-brittle transition temperature of tungsten and improved the mechanical properties of the material.Subsequently,through microstructure analysis,it was found that some HfC particles could absorb oxygen impurities in the tungsten matrix and form Hf-C-O or HfO2 compounds in the sintering process,which to some extent reduced the concentration of free impurity oxygen in the matrix,enhanced the binding force of the tungsten grain boundary and improved the mechanical properties of the material.On the basis of optimized components,W-0.5%HfC alloy bar with high density was prepared by powder metallurgy combined with high temperature rotary forging.The ductile-brittle transition temperature of the spiraled W-0.5%HfC alloy was 250?.At 250?,the ultimate tensile strength and total elongation of the bar were 800 MPa and 4.1%,respectively.The hot rolled WHC05 grain had obvious rod-like morphology,with an average width of 24.5 ?m and an average length of 187 ?m.The annealing temperature is 1200? rolled WHC05 alloy at 800? the ultimate tensile strength of 300 MPa,ultimate tensile strength was not significantly reduced in the test temperature range.1200? after annealing spin rolled WHC05 coefficient of thermal conductivity at room temperature up to 174 W/mK,within the scope of RT ? 500 0C is always greater than 137 W/mK,far higher than that of without annealing WHC05,same as the level of ITER W.On the basis of previous experiments,W-0.5wt.%HfC(WHC05)alloy was prepared by conventional sintering and multi-step hot rolling method.WHC05 recrystallization temperature of the alloy(1400? to 1500?)compared to the original report rolling pure W(1200 0C)and rolling W-0.5wt.%ZrC(WZC05?1300 0C)high.In addition,the response and recrystallization(1600? annealing),after WHC05 alloy maintain high ultimate tensile strength?300 MPa,showing an ideal total elongation increases(>35%)?1.6 times higher than that of recrystallization WZC05 at 500 0C.Superior thermal stability and excellent high temperature mechanical properties can be attributed to the rolling sample in unique microstructures such as elongated mother crystals and nanoscale equiaxed subcrystals and dispersion enhancement of hafnium carbide particles in the second phaseThe properties of tungsten alloys related to fusion applications were tested by simulating the fusion environment.The cracking threshold of the rolled WHC05 alloy is 330 MW/m2?440 MW/m2,while there is little damage to the material below 330 MW/m2.The irradiation resistance of rolled WHC05 alloy is better than pure tungsten.Deuterium hold up in pure tungsten by TDS was much higher than that in WHC05 sample.In this paper,by continuously optimizing the preparation method and processing technology of tungsten-based materials,combining the mechanism of interface synergy and the second phase dispersion strengthening,it provides a feasible idea for the preparation of high-performance bulk tungsten alloys,and it provides useful guidance for practical application of tungsten-based materials in fusion reactors in the future.