Plastic deformation of single crystals of VSi2 and TaSi2 with the C40 structure

Abstract

Abstract The deformation behavior of (0001)〈1210〉 basal slip in single crystals of VSi2 and TaSi2 with the C40 structure has been investigated in the temperature range from room temperature to 1500 °C in compression. Plastic flow is observed only above 400 and 600 °C for VSi2 and TaSi2, respectively. The critical resolved shear stress (CRSS) for basal slip decreases with increasing temperature but exhibits a moderate peak around 1100 and 1400 °C for VSi2 and TaSi2 respectively. Dislocations with b = 1 3 〈1210〉 gliding on (0001) basal planes both in VSi2 and in TaSi2 are observed to dissociate into two identical partials with b = 1 6 〈1210〉 involving a stacking fault. High-resolution transmission electron microscopy of 1 3 〈1210〉 dislocations indicates that basal slip both in VSi2 and in TaSi2 occurs through a conventional single shearing mechanism, unlike in isostructural CrSi2 and Mo(Si,Al)2 in which basal slip occurs through a synchroshear mechanism.