Analysis of the Grain Size Dependence of the Yield Stress in Copper-Aluminum and Copper-Nickel Alloys

Abstract

Grain size dependence of the yield stress in polycrystalline copper-aluminum and copper-nickel alloys is measured at 77, 194 and 293°K. It is found that the Hall-Petch relation is valid for these materials. The Petch slope k_y is nearly independent of the temperature, but increases with increasing solute concentration. In copper-aluminum alloys the increase in k_y is nearly proportional to the square root of the solute concentration, while in copper-nickel alloys it is proportional to the concentration itself. The concentration dependence of k_y, in Cu–Al alloys is considerably larger than that in Cu–Ni alloys. None of previously proposed theories on the Petch slope can explain these results. The experimental results will be compared with the calculation in the following paper.