Development of directionally solidified Ni-Al-Mo-B-Y alloy IC6A

Abstract

A directionally solidified Ni₃Al based alloy designated IC6A with the chemical composition Ni - (7.5 - 8.5)Al - (13.0 - 15.0)Mo - (0.02 - 0.1)B - (0.001 - 0.20)Y (wt-%) has been recently developed as a high-temperature structural material for advanced jet-engine vanes operating in the temperature range 1050 - 1100 ° C. Microstructural analysis results show that the regions consisted of Ni₃Y, Mo₁.₂₄Ni₀.₇₆ and γ phases and surrounded by large size γ ′ phases precipitate in the interdendritic areas of alloy IC6A when the content of yttrium is near to the upper limit. Ni₃Y and Mo₁.₂₄Ni₀.₇₆ have no obvious change during high temperature aging. A needle like or rod like phase named Y - NiMo precipitates after aging at 950 ° C for about 200 h. The high temperature cyclic oxidation resistance of alloy IC6A is fairly good owing to the presence of yttrium. The tensile properties, high temperature stress rupture properties and creep properties, high cycle fatigue properties and impact toughness of alloy IC6A were investigated to meet the needs of aeroengine turbine vanes.