Method for preparing tungsten material through nanophase separation and sintering

Abstract

The invention provides a method for preparing a tungsten material through nanophase separation and sintering. According to the method, mechanical alloying powder with the features of nanocrystalline grain structures and a supersaturated solid solution is prepared through high-energy ball milling and then is densified through pressureless sintering and unsheathed hot isostatic pressure technologiesto obtain a tungsten matrix composite. In the sintering process, nanocrystalline grains and the supersaturated solid solution are subjected to phase separation, nano precipitated phases are preferentially precipitated on the necks of the nanocrystalline grains and the surfaces of powder particles to form a quick migration channel, sintering densification is promoted, and the sintering temperatureis lowered. Along with rising of the sintering temperature, the nano precipitated phases are diffused to a tungsten matrix, and a grain boundary element enrichment region is left. Grain growth can beeffectively suppressed through comprehensive utilization of a grain boundary element segregation region and secondary phases. The method has the advantages that solid phase sintering is conducted inthe sintering process; the sintering temperature is low; the secondary phases are prevented from growing obviously in the high-temperature sintering process; the method is suitable for preparing a large-size fine grain tungsten matrix material; the prepared tungsten matrix material is almost fully densified, uniform in texture structure and excellent in comprehensive mechanical performance.

Description

technical field [0001] The invention belongs to the technical field of sintering and densification of refractory metals, and in particular provides a method for preparing tungsten materials by nano phase separation sintering. Background technique [0002] Tungsten has excellent properties such as high melting point, high thermal conductivity, low vapor pressure, low sputtering yield, and low tritium retention, but there are problems such as high ductile-brittle transition temperature, low recrystallization temperature, and radiation embrittlement. Using methods such as grain refinement and second-phase particle (carbide, oxide) doping to make the grain refinement and nanometerization of tungsten materials is the most promising way to improve the plasticity, toughness and radiation resistance of tungsten materials. method. In nanocrystalline tungsten materials, nano-grains, a large number of high-angle grain boundaries, and nano-second phases can not only strongly hinder the...

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Problems solved by technology

However, this method mainly relies on the grain boundary enrichment zone to suppress the grain growth, which has low stability in the process of high temperature use. The pinning effect of misalignment is weakened, which will lead to the growth of grains and the decline of high temperature mechanical properties

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