Effects of Ni-additive on the grain growth of tungsten wire

Nickel added to W wire accelerated the recrystallization grain growth. Based on the measured growth exponent, the grain growth kinetics seem to be controlled by a grain boundary reaction in the initial stage of grain growth, but the value of the exponent approaches slowly to that value characterized by a diffusion controlled process with increasing grain growth. The grain growth kinetics of W in the presence of a small amount of nickel seem to be different from that of W-Ni during liquid phase sintering. The rate constant for grain growth increased with increase of Ni interlayer thickness, which is contrary to the relation found in liquid phase sintering of W-Ni. The microstructural development is simillar to that developed in liquid phase sintering.