Factors Influencing the Recrystallization of Non-Sag Tungsten Wires Indicated by the Out-Diffusion of Cobalt

In Al, , Si doped (AKS) tungsten wires, the socalled recrystallization temperature, TSR, rises to a very high value due to the pinning effect of bubble rows against grain growth. However, T SR can also be influenced by several other factors, like: intermediate heat treatments during wire drawing, annealing the wire at different temperatures or times, or applying further strain e.g. by coiling or torsion. As a model material, AKS tungsten wire with an excess cobalt dope was investigated, in which the variations in the solute cobalt content were easily followed by measuring thermoelectric power. In this way e.g. diffusion governed processes, like segregation-desegregation, the rapid or slow out-diffusion of Co and the effect of different heat treatments on T SR can also be investigated.