Optimizing microstructure and mechanical properties of NiAl-9Mo alloy by Zr addition and suction casting process

Abstract

In the present work, NiAl-9Mo alloys with different addition of Zr were prepared by water--cooled copper mold and suction casting, respectively, and the influence on the microstructure and properties of the alloys was discussed. The results show that the microstructure of the as-cast NiAl-9Mo-xZr (x = 0.5, 1.0, 1.5) alloys is a typical eutectic cell structure, with Ni2AlZr (Heusler) phases discontinuously distributed in the cell boundaries. The eutectic cells of NiAl--9Mo-1Zr alloy prepared by the suction casting process are refined, and the average eutectic lamella thickness is about 3 µm. The microhardness of the suction-cast NiAl-9Mo-1Zr alloy is 630.0 HV, which is higher than that of the as-cast alloy (396 HV). The high-temperature compressive strength of the as-cast NiAl-9Mo-1Zr alloy is higher than that of the as-cast alloy, which reaches 350 MPa at 1273 K, due to the joint action of fine grain strengthening and the second phase strengthening of the Heusler phase.