IMPROVEMENT OF OXIDATION RESISTANCE AND MECHANICAL PROPERTIES BY THE ADDITION OF YTTRIUM AND SILICON IN A Ni_3Al BASE ALLOY IC6

The oridation resistance at 1100°C of a dirationally solidified Ni3Al base alloy IC6is substantially improved by the addition of yttriurn or yttrium and silicon. The stress rupture property under 1100°C/80MPa is increased by adding proper amounts of yttrium, howevef it decreases bg adding 0.3wt% silicon and 0. 1wt% yttrium at the same time, which may be attributed to the formation of a needle like phase rich in nickel and molybdenum.