Transmission electron microscopy analysis of planar faults on (001) planes in MoSi₂ single crystals

Abstract

Planar faults on (001) planes were formed during in-situ annealing and straining experiments on MoSi₂ single crystals in a high-voltage electron microscope. As-received and pre-deformed crystals grown by either the float-zone or the Czochralski technique were exposed to temperatures between 400 and 1200°C. The faults are only formed if dislocations with ½〈111〉 Burgers vectors are present. The faults and the bordering partial dislocations were characterized by a transmission electron microscopy contrast analysis. The two partial dislocations bordering a fault have different types of Burgers vector. It is suggested that the faults result from a dissociation reaction according to ½[111]=½[110] + ½[001], leading to intrinsic stacking faults on (001) planes. Probably, similar microstructural mechanisms control both the formation of the faults and the flow stress anomaly of the 〈111〉{110} slip system in MoSi₂.