Abstract
MoSi~2~ single crystals were deformed along the soft 〈110〉 compression axis between room temperature and 1050 °C. The strain rate sensitivity of the flow stress was determined by stress relaxation tests. The temperature dependence of the flow stress shows three temperature ranges, a low and a high‐temperature range with a normal decrease of the flow stress with increasing temperature and an intermediate range with an anomalous flow stress increase. In the latter range, the strain rate sensitivity decreases (inversely) with increasing strain rate. The dislocation structures of the deformed samples were imaged in diffraction contrast in a high‐voltage electron microscope. In contrast to the low and high‐temperature ranges, the dislocations are straight and oriented along 〈111〉 directions in the anomaly range. The results are interpreted by a large athermal stress component, the action of the Peierls mechanism in the low temperature range, a new dissociation model of the dislocations requiring conservative climb in the dislocation core in the anomaly range, and recovery‐controlled deformation in the high‐temperature range. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)