Evaluation of High Temperature Strength and Functional Characteristics in Sintered Tungsten Alloy without Radioactive Particle

Abstract

In order to find the alternative tungsten alloys to the radioactive Thoria-Tungsten alloy (ThO₂-W), the carbide added tungsten alloys (HfC-W and TaC-W) were fabricated by the sintering process. Emission current density was measured to evaluate thermal electron emission property. The thermal electron emission current density of HfC-W was the highest among TaC-W, ThO₂-W and W. Tensile tests were carried out at room temperature and elevated temperature of 1573 K and 1773 K. Particles added tungsten alloys showed higher strength compared to tungsten alloy without particles. Grain growth might be suppressed by adding particles, particularly in carbides. Carbides, HfC and TaC distributed among grain boundary could effectively suppress grain growth during sintering and high temperature testing. The highest tensile strength with higher stability of mechanical properties at elevated temperature was obtained in HfC-W among TaC-W, ThO₂-W and W. Therefore, it could be concluded that HfC-W would be one of the most promising thoria-free tungsten alloys. Thermal electron emission property and high temperature tensile property were also evaluated in sintered ThO₂-W alloy and forged ThO₂-W alloy which experienced forging process followed by sintering process. Electron emission current density and tensile strength at room and elevated temperatures were almost comparable in the ThO₂-W alloys regardless forging process.