High temperature deformation behaviour of MoSi₂ and WSi₂ single crystals

Abstract

High temperature deformation behaviour of MoSi₂ and WSi₂ single crystals, which both oriented near 〈001〉 and near 〈100〉, have been studied by compression tests over the temperature range of 1100 to 1500° C in a high vacuum of less than 6×10⁻⁴ Pa. At elevated temperatures, several per cent compression deformation is possible in both MoSi₂ and WSi₂. Slips on {110∼ and {013∼ planes, the dislocation with the direction of Burgers vector 〈331〉 and the stacking fault on {110∼ plane are observed in both deformed MoSi₂ and WSi₂. In MoSi₂, the 0.2% offset stress of the sample oriented <001> is higher than that of the sample oriented <100>. The higher strength of the sample oriented <001> is related to the higher CRSS for the main slip plane of it. The reverse orientation dependence of the strength in WSi₂ is also correlated with the difference in CRSS on {110∼ and {013∼ planes, which shows the opposite result to MoSi₂. The higher CRSS on {110∼ plane in WSi₂ compared to that on {013∼ may be caused by the formation of a large number of stacking faults on {110∼ plane.