The flow stress of Cu3Au

Precision compression flow stress measurements were made on single crystals of Cu3Au over the temperature range 77°k to 695°k. The temperature dependence of the flow stress from 77°K to about 200°K is similar to that observed in pure f.c.c. metals. The flow stress at elevated temperatures increases markedly, as has been previously observed. A new theory is presented here in which this increase in flow stress at elevated temperatures is interpreted in terms of a modulus interaction between moving dislocations and local regions of disorder within the ordered matrix. As the temperature is raised these regions become more numerous as the long-range order parameter decreases and the flow stress rises. Very satisfactory correlations can be made between the theory and the flow stresses reported here.