Effects Of Zr, Nb, Ti On The Microstructure And Property Of The NiAl-9Mo Alloy

The effect of small amount Zr, Nb or Ti elements on microstructure, hardness and hightemperature compressive properties of the NiAl-9Mo eutectic alloy were studied.The microstructure of the cast NiAl-Mo-Zr alloy is typically eutectic and with theNi₂AlZr （Heusler） phase at the cell boundary. The microstructure of NiAl-Mo-Zr alloy iscomposed of the black gray NiAl matrix and grey white Mo phase. The microstructure of thesuction cast alloy is the same as the cast alloy; however the microstructure of the suction castalloy is much thinner than that of the cast alloy. The microstructure of NiAl and Mo does notbasically change after heat treatment. But Heusler phases disappear partly or totally. With thecontent of Zr increasing, the hardness of the cast NiAl-Mo-Zr alloy increases. The hardnessand the compressive yield strength of the suction cast alloy are superior to the cast alloy.The microstructure of NiAl-Mo-Nb alloy is composed of the black NiAl phase, the whitegray Mo phase, there is no NiAlNb（Laves） phase. The microstructure of NiAl and Mo doesnot basically change after heat treatment. The microstructure of the suction cast alloy is thesame as the cast alloy; however the microstructure of the suction cast alloy is much thinnerthan that of the cast alloy. With temperature increasing, the compressive yield strength of thecast NiAl-Mo-0.5Nb alloy decreases. The hardness and the compressive yield strength of thesuction cast NiAl-Mo-1.0Nb alloy are superior to the cast NiAl-Mo-1.0Nb alloy.The microstructure of the cast NiAl-Mo-Ti alloy is typically eutectic cell. It is composedof the black gray NiAl matrix and grey white Mo phase, and there is no Ni₂AlTi（Heusler）phase. The microstructure of the suction cast alloy is the same as the cast alloy; however themicrostructure of the suction cast alloy is much thinner than that of the cast alloy. With thecontent of Ti increasing, the hardness of the cast NiAl-Mo-Ti alloy increases. The hardness ofsuction cast alloy is higher than that of the cast alloy.The hardness and the compressive yield strength of the NiAl-Mo alloys containing Zr,Nb or Hf are higher than the NiAl-9Mo alloy, and the hardness of the NiAl-Mo-0.5Zr alloy isthe highest. The hardness and compressive yield strength of the suction cast NiAl-Mo-1.0Zralloy is higher than that of the suction cast NiAl-Mo-1.0Nb alloy, and also higher than that ofthe suction cast NiAl-Mo-1.0Ti alloy.