Deformation mechanisms in MoSi2 at temperatures above the brittle-to-ductile transition temperature .2. Single-crystal MoSi2

The mechanisms which contribute to the plastic deformation of the intermetallic compound MoSi2 have been determined for single-crystal specimens of MoSi2, (Mo0.99Nb0.01)Si-2 and (Mo0.9925Ti0.0075)Si-2 oriented along [13(1) over bar] compressed at 1400 degrees C and at a strain rate of 10(-5) s(-1) in vacuum. The results of compression testing of the three single crystals show significant differences between the yield stress values. For the binary MoSi2 single crystal, the yield stress was found to be 34 MPa, and for the (Mo0.99Nb0.01)Si-2 and (Mo0.9925Ti0.0075)Si-2 crystals values of 79 and 38 MPa respectively were recorded. An apparent violation of Schmid's law was found in deformation of samples of two of the crystals, namely the binary and Ti-containing version. Thus, while in the Nb-containing compound, the expected slip system, 1/2 (111){110}, was activated; this was not the case in the other two compounds. An alternative explanation involves the influence of climb, this being similar to the conclusions drawn in part I for polycrystalline MoSi2.