TEMPERATURE AND ORIENTATION DEPENDENT PLASTIC-FLOW IN PT3AL

The compressive flow stress of Pt3Al single crystals was measured as a function of temperature and orientation of the compression axis to check the predictions of the theory of Tichy et al. regarding the operative slip systems. It was found that samples oriented near [001] slip predominately on (111) planes, while those oriented on the opposite side of the triangle slip on (001) planes. The temperature dependences of the critical resolved shear stress (CRSS) for (111) and (001) slip are similar, viz, the CRSS increases dramatically with decreasing temperature from an almost constant value at elevated temperatures. The CRSS for cube slip is always less than that for octahedral slip. The transition from octahedral to cube slip occurs over a small range of orientations, as predicted by the Tichy et al. model, but slip on only one system was observed in samples of a given orientation.