SOLID-SOLUTION SOFTENING AND HARDENING IN ALLOYED MOSI2

Alloying effects on the micro-Vickers hardness of MoSi2 were investiga ted experimentally. The microhardness was measured at temperatures in the range from 293 to 1473 K. It first decreased rapidly with increasi ng temperature, and then showed either a plateau region or even a smal l peak at the temperature range of about 900 to 1200 K, and finally it decreased rapidly again with temperatures. The microhardness was modi fied considerably by alloying. For example, it increased largely by th e addition of W and Re into MoSi2, due to the solid-solution hardening , whereas it decreased by the addition of Cr, Zr, Nb, Ta and Al into M oSi2, due to the solid-solution softening. Such microhardness changes with alloying elements, M, correlate with the microhardness of the cor responding MSi2 disilicides. (C) 1998 Elsevier Science Limited. All ri ghts reserved.