Determination of recrystallization temperature of Ta-2.5W alloy

Ta and W are both high-density and rare refractory metals, in which the melting point of Ta is 2996℃, with good mechanical properties, high thermal conductivity, stable chemical properties, strong corrosion resistance and other advantages. According to the characteristics of Ta and W, the Ta-2.5W alloy developed has the characteristics of high temperature resistance, high density, chemical stability and good processing performance. It is an indispensable important material in aerospace, chemistry, nuclear industry, high temperature technology and other fields, and has a good application prospect.

There are two main preparation methods of tantalum tungsten alloy, namely powder metallurgy and electron bombardment smelting. Powder metallurgy has high requirements for tantalum and tungsten powder, and the ingot produced by powder metallurgy has high content of impurities and low relative density, which will directly affect the subsequent processing properties and use properties of the material. The electron bombardment smelting method can effectively remove all kinds of impurities in the material, especially the harmful low melting point impurities, and the structure of the ingot is compact, and its relative density is significantly higher than that of the ingot obtained by powder metallurgy. In addition, the electron bombardment smelting method does not require high raw materials, metallurgical grade tantalum powder and tungsten powder can be used. However, the coarse grain size of the ingot obtained by electron bombardment smelting method is 3~5mm on average, which is unfavorable to the mechanical properties of the material. Therefore, it is necessary to refine the grain size through the combination of deformation and recrystallization annealing, so as to improve the microstructure of the material and improve its processing and mechanical properties. Recrystallization of Ta-2.5W alloy forging bar occurs at about 1450℃ : after 86% cold deformation in a single pass, recrystallization occurs at about 1400℃.