PLASTIC-DEFORMATION OF MG2SI WITH THE C1 STRUCTURE

Coarse-grained crystals of MgSi2 with the Cl structure, produced by me lting and slow cooling of constituent elements in a sealed molybdenum ampoule, have been compressed in vacuum at high temperatures. The crys tals were brittle below 500 K and underwent plastic deformation above 550 K; the yield strength decreased rapidly with increasing temperatur e down to 10 MN/m(2) above 900 K. Transmission electron microscopy rev ealed that the plastic deformation was carried by glide of dislocation s with the Burgers vector of 1/2[1 1 0]. It is concluded, based on the thermal-activation analysis of plastic deformation, that the deformat ion is controlled by the Peierls mechanism. Copyright (C) 1996 Elsevie r Science Ltd.