Deformation Mechanisms in the Intermetallic Compound MoSi₂

Abstract

The nature of dislocations which have been activated during plastic deformation of MoSi₂ at 1400°C in compression have been identified using transmission electron microscopy. Particular attention has been paid to the possible dissociation of dislocations, and it has been confirmed that dislocations with Burgers vectors lying parallel to <111> are dissociated. The dissociation is represented by:

$1/2 < 111 > \, \to \,1/4 < 111 > + \,{\text{SISF + 1/4 < 111 > ,}}$

where SISF stands for superlattice intrinsic stacking fault. The SISF energy has been estimated from the separation of the partial dislocations to be ≈ 255 mJ.m^-2. A simple explanation to account for the occurrence of dissociation for particular dislocations is presented.