RECRYSTALLIZATION OF TUNGSTEN WIRE INDUCE D BY NICKEL DIFFUSION

Various annealing on nickel coated tungsten wires have been performed and have determined a critical annealing temperature of 1000 degrees C . Above this temperature a phenomenon of recrystallization is produced by an intergranular diffusion of nickel in the fibrous microstructure of the tungsten. Tensile tests have shown the brittle feature of this microstructural transformation and also the effect of the doping with potassium on tungsten wires. This recrystallisation is related to a p henomenon called D.I.G.M. (Diffusion Induced Grain boundary Migration) but our system seems to be a particular case because it needs to find another hypothesis with respect to the driving forces and mechanisms to explain this phenomenon of recrystallization.