Recrystallization and Respheroidization of Tungsten Grains in a Tungsten-Heavy Alloy

摘要

Refinement of the microstructure of tungsten-heavy alloys, specifically 90 W-7 Ni-3 Fe, has been achieved through heavy cold working followed by a heat treatment that recrystallized and respheroidized the tungsten grains. Hydrostatic extrusion of the alloy to reductions of area of 83% and 96% followed by isothermal annealing gives fine, spherical tungsten grains imbedded within the nickel-iron matrix. The finest grain size achieved was 15 microns for the 96% extrusion when subjected to an anneal at 1300 C for 2 hours. The apparent activation energy for the process was found to be 530 kJ/mole. This value indicates that volume diffusion is significant in respheroidizing the grains. (AW)