Effect of high temperature aging on microstructure and mechanical properties of a directionally solidified Ni_3Al base alloy IC6A

摘要

The effect of aging at 950?℃ for up to 2?000?h on microstructure and mechanical properties of alloy IC6A was investigated with scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive spectroscopy(EDS) of electron probe micro analyzer(EPMA). The results show that Ni 3Y and Mo 1.24 Ni 0.76 precipitated in the interdendritic area due to the addition of yttrium have no obvious change during high temperature aging. A needle like or rod like phase named Y NiMo precipitated after aging for about 200?h. The amount and size of the Y NiMo phases increase with the increase of aging time, which is similar with that in alloy IC6. The ultimate tensile strength at room temperature and stress rupture life under 1?100?℃, 90?MPa of alloy IC6A have no obvious change before aging for 1?000?h and decrease obviously with increasing aging time after aging for 1000h. The yield strength of alloy IC6A at room temperature decreases obviously after aging for 500h and however, has no obvious change during further aging.