Effect of long term aging on microstructure and mechanical properties of Ni₃Al base alloy IC6

The effect of long term aging at 950°C for 500, 1000, 1500 and 2000 h on the microstructure and mechanical properties of alloy IC6 was investigated. The results showed that some fine rod-like Y-NiMo phases precipitated from γ-phase in the beginning 10 h, and some needle like Y-NiMo phases precipitated after aging for 50 h. The amount and size of Y-NiMo phases increased obviously with the increment of aging time up to 1000 h, and had almost no change when continued aging to 1500 h, while decreased slightly after aging for 2000 h. The borides in alloy IC6 had no change during aging. The yield strength and elongation of alloy IC6 at room temperature decreased obviously after aging for 500 h and however, had almost no change during further aging. The ultimate tensile strength at room temperature of alloy IC6 had no obvious change during aging. The stress rupture life under 1100°C. 90 MPa of alloy IC6 decreased with aging time up to 1000 h and increased obviously after aging for 2000 h due to the transformation of Y-NiMo phase to γ-phase.