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

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 – {11¯00}[0 0 0 1] prismatic slip, {21¯1¯2}1/3〈21¯1¯3¯〉 pyramidal slip and {21¯1¯8}〈84¯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 (CRSSs) decrease steeply with increasing temperature for all deformation modes. The values of the CRSSs for {11¯00}[0 0 0 1] prismatic slip are considerably lower than those for {21¯1¯2}1/3〈21¯1¯3¯〉 pyramidal slip, but are comparable to those for {21¯1¯8}〈84¯4¯3¯〉 twinning. The favored deformation modes are discussed on the basis of anisotropic elasticity theory of dislocations.