GRAIN-GROWTH IN COPPER AND ALPHA-BRASSES

The wires of 99.999% copper and alpha-brasses containing 12, 20, 30 and 35 at % Zn have been annealed in vacuum for 30 to 240 min at 873, 923, 973 and 1023 K. The grain-growth data obtained are well encompassed by the relation D2, -D02, =Kt exp(-H/kT), where D is the instantaneous mean grain diameter at the time, t, of isothermal anneal and D0 refers to the initial mean grain diameter. In alpha-brasses the activation energy for grain-boundary self-diffusion, H, and the pre-exponential factor, K, depends on the zinc concentration, c, as H = (H0 - 1.1 c) eV and K =K0 exp(-10.7 c) cm2 sec-1. The values of H0 and K0, referred to the base metal are respectively 0.87 eV and 3.0 × 10-4 cm2 sec-1, which are in good agreement with those (0.85 eV and 3.6 × 10-4 cm2 sec-1) found for copper. © 1990 Chapman and Hall Ltd.