PRISMATIC AND BASAL SLIP IN TI3AL .1. FRICTIONAL FORCES ON DISLOCATIONS

In situ straining experiments have been conducted in polycrystalline T i3Al, with the aim of analysing the mechanisms controlling dislocation motion and interpreting the mechanical properties. This first part is devoted to the glide process of 1/3 [<11(2)over bar 0>] dislocations in prismatic and basal planes. Antiphase boundary (APE) energies have been measured in these planes. Two different APE energies and two diff erent frictional forces have been observed in parallel prismatic plane s, corresponding probably to two different cutting planes. The high Pe ierls-type frictional forces which have been observed in the basal and in one type of prismatic plane are shown to originate from non-planar dislocation cores, in agreement with recent atomistic calculations.