STRENGTH ANOMALY OF β-CuZn

Mechanical properties of single crystals of β-brass have been studied extensively as functionsof deformation temperature and orientation. Yield stresses show anomalous peaks at around 200°C,the exact peak temperature (Tp) depending on both orientation and mode in which crystals aredeformed., i.e. tension, compression or direct shear. Dislocation structures have been observed com-prehensively using transmission electron microscopy. Below Tp , <111> dislocations are activated,while above Tp , non-<111> dislocations such as <100> and <110> dislocations are activated. Inaddition between room temperature and Tp, where the yield stress shows an inverse temperaturedependence, <111> dislocations are climb-dissociated. The climb dissociation of <111> disloca-tions below Tp and transition of slip direction across Tp are attributed to the strength anomaly inβ-brass. However, a β-brass single crystal with orientation χ= 30° shows very peculiar plasticity,which can not be explained easily at the moment.