EFFECT OF GRAIN-BOUNDARY DIFFUSION FLUXES OF COPPER ON THE ACCELERATION OF CREEP IN SUBMICROCRYSTALLINE NICKEL

Experiments were conducted on the effect of grain boundary diffusion f luxes of Cu on creep behaviour of coarse-grained and submicrocrystalli ne (SMC) Ni. For both grain sizes, the creep rate is accelerated by th e diffusional fluxes of Cu in the grain boundaries. However, the effec t occurs in a lower temperature range for the finer grain size SMC mat erial. The grain boundary diffusion coefficients of Cu in SMC nickel w ere experimentally measured at the temperatures of 423 K and 573 K. Th e grain size dependence of the creep acceleration behavior can be attr ibuted to higher diffusivity in the finer grain material.