Plastic deformation of single crystals of Ti5Si3 with the hexagonal D88 structure

Abstract

The deformation behavior of Ti5Si3 single crystals with the hexagonal D88 structure has been investigated in compression as a function of crystal orientation in a temperature range from 1200 to 1500°C. Three different types of deformation modes: {1¯100}[0001] prismatic slip, {2¯1¯12}1/3<2¯1¯1¯3> pyramidal slip and {2¯1¯18}<8¯4¯4¯3> twinning were identified for the first time as being operative in Ti5Si3 at temperatures above 1300°C, depending on the loading axis orientation. The critical resolved shear stresses (CRSS) decrease steeply with increasing temperature for all deformation modes. The values of the CRSS for {1¯100}[0001] prismatic slip are considerably lower than those for {2¯1¯12}1/3<2¯1¯1¯3> pyramidal slip, but are comparable to those for {2¯1¯18}<8¯4¯4¯3> twinning. The favored deformation modes are discussed on the basis of anisotropic elasticity theory of dislocations.