The grain size dependence of flow stress in a Cu-26Ni-17Zn alloy

The effect of grain size in the range 15-120 mu m on flow stress was studie d at room temperature to investigate the Hall-Fetch relationship in a Cu-26 Ni-17Zn alloy. It was found that the Hall-Fetch relation is valid for the a lloy. The Hall-Fetch constants, sigma(o epsilon) and k(a) are related to tr ue strain (epsilon) in such a way that sigma(o epsilon) is proportional to epsilon and k(epsilon) to epsilon(1/2). An equation for flow stress as a fu nction of true strain and grain size has been derived from these results. D islocation density model for grain size strengthening is found valid for th is alloy. Solid solution strengthening in the Cu-26Ni-17Zn alloy is attribu ted to the interaction of nickel and zinc atoms with screw dislocations and the effective interaction is more due to modulus mismatch than size misfit . (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All ri ghts reserved.