The Study On Microstructure And Mechanical Properties Of Carbide Particle-reinforced Tungsten-matrix Alloy

The refractory metal tungsten has a high melting point, good oxidation resistance, low vapor pressure, high self-sputtering threshold, and other characteristics, and thus widely used in high temperature areas, but due to pure tungsten density is too high, insufficient high temperature strength decreased significantly and so on, limiting its application in the more high-temperature service conditions. In the paper, carbide particles are added due to their excellent properties such as high melting point, low density, favorable high temperature strength, and the similar coefficient of thermal expansion with tungsten, and expect to reduce the tungsten matrix density, but also increase the mechanical properties.In this paper, the W-(2-10)%TiC alloy and W-(l-5)%of ZrC alloy was prepared by conventional hydrogen atmosphere sintering method, the densification behavior and mechanism are studied, meanwhile, the sintering temperature effect and carbide composition on the mechanical properties, but also the microstructural structure of the W-TiC and W-ZrC alloy are discussed. The results show that:(1) The densification temperature range for the W-TiC alloy is1500～1700℃, after sintering at1700℃, the W-TiC alloy, especially the W-6TiC alloy close to full density; with the sintering temperature, the tensile strength of the W-TiC alloy improved in sintered at2000℃for2h, the tensile strength of W-6TiC alloy up to464MPa;(2) The densification temperature stage for W-ZrC alloys is the range of1600-2000℃, the W-ZrC alloy close to full density after2000℃sintering, moreover, the W-ZrC alloy achieved maximum density with ZrC content of3wt%, the W-of ZrC alloy tensile strength increased with the sintering temperature improved, sintered at2000℃, W-ZrC alloy strength up to489MPa with3%ZrC content;(3) The small dispersion complex particle phase generated during the high-temperature sintering process, which effectively hampering the W grain growth; meanwhile, with the increase of the sintering temperature, the diffusion of atoms between W-TiC and W-ZrC improved, therefore, solid solution generated enhanced the W-TiC and W-ZrC grain boundary strength; however, excessive amount of second phase particles TiC and ZrC formed particle aggregation regionin at the grain boundaries of the W and tended to rupture easily, which deteriorated the strength of the alloy.