Effect of cobalt addition on grain growth kinetics in Cu-Zn-Al shape memory alloys

beta-phase in copper alloys present a rapid growth. Coarse grain size materials should be avoided since they decrease the uniformity and reproducibility of properties, they can cause pseudoelastic brittleness and they decrease the stress-corrosion resistance. The grain size produces changes in the transformation temperatures and in the stress required to induce the martensitic phase. The purpose of this work is to show the effect of cobalt addition on grain growth kinetic in Cu-ZnAl shape memory alloys. The cobalt was added with the purpose of refining the grains. Grain growth kinetics have been evaluated in Cu-Zn-Al shape memory alloys with different cobalt contents by the calculation of several grain-size parameters (perimeter, area and diameter) at different temperatures and heat treatment times. The growth exponent values have been determined and the activation energies estimated. (C) 1998 Published by Elsevier Science Limited. All rights reserved.