HIGH-TEMPERATURE DEFORMATION-BEHAVIOR OF MOSI2 AND WSI2 SINGLE-CRYSTALS

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. © 1990 Chapman and Hall Ltd.