High temperature oxidation of MoSi2-WSi2 solid solutions

The effect of WSi2 solute on the oxidation behavior of MoSi2 was investigated in a wide temperature range of 773 K to 1773 K in air. MoSi2 and WSi2 individually have outstanding oxidation resistance at high temperatures such as 1773 K as a result of the selective oxidation of Si. Such passive oxidation behavior occurs also in all MoSi2-WSi2 solid solutions. On the other hand, at lower temperatures, especially at medium temperatures like 1073 K, accelerated oxidation which is based on the simultaneous oxidation of W and Si takes place for the 50% WSi2 composition. In addition, it was experimentally confirmed that the preoxidation treatment at higher temperature is effective for prevention of the accelerated oxidation. (orig.)