The effect of temperature on the deformation modes of the ζ copper-germanium phase

Abstract

Single crystals of the ζ Cu-Ge intermediate phase of nominal compositions 13·5 and 16·2 at.% Ge were tested in the temperature range 4·2°k–1000°k approximately. The yield drop in basal slip could be reduced by quenching for test temperatures below 420°k, but for test temperatures above this, the type of heat treatment did not have any appreciable effect upon the yield behaviour. τu.y.p. for both of the quenched alloys was temperature dependent in the range below 400°k approximately. In all other cases where a yield point occurred, the results showed considerable scatter. Crystals of the 13·5 at.% Ge alloy oriented for non-basal slip cleaved over the entire temperature range used without any apparent non-basal slip deformation. In contrast, crystals of the 16·5 at.% Ge alloy showed extensive {1010} 〈1 120〉 slip, with no yield point at all. The yield point in basal slip is thought to be due to the Suzuki and Cottrell mechanisms.