COMPATIBILITY OF DEFORMATION IN 2-PHASE TI-AL ALLOYS - DEPENDENCE ON MICROSTRUCTURE AND ORIENTATION RELATIONSHIPS

A two-phase alloy of composition Ti-47.5A1-2.5Cr has been studied under two heat-treated conditions in order to obtain different microstructures. These consisted of lamellar and equiaxed distributions of gamma grains in which the alpha(2) phase was distributed as long lamellae or smaller globules, respectively. The specific rotation relationships between gamma/gamma and gamma/alpha(2), grains have been measured, and these have been used to understand their effect on the compatibility of deformation across adjacent grains. For this, detailed analysis of active slip systems has been carried out by transmission electron microscopy (TEM) observations of deformed samples. A theoretical calculation of a geometric compatibility factor characterizing the best slip transfer across adjacent grains has been used in such a way that it has been possible to deduce the role played by the type of orientation relationship between grains in producing active deformation systems that allow the maximum compatibility of deformation.