Microstructure and Tensile Property of NiAl-Cr Alloyed with Zr

Abstract

The microstructure of as-cast NiAl-33.5Cr-0.5Zr alloy is the eutectic colonies of NiAl and Cr phase with non-continuous Heusler (Ni2AlZr) phase segregating at the cell boundaries. After hot isostatic press (HIP) processing at 1573K, 100MPa for 2h, the Ni2AlZr phase changes into Zr-rich phase. The elevated temperature tensile strength and elongation of the HIP-ed alloy are much higher than those of as-cast alloy. It was noted that this alloy either as-cast or HIP processing exhibits a brittle to ductile transition behavior, which is difference between as-cast and HIP-ed alloy. HIP processing decreases the BDTT of the alloy, especially in high strain rates, and lower the range of BDTT. When the strain rate increases by two orders of magnitude, the BDTT has an approximate increase from150K for as-cast alloy to 100K for HIP-ed alloy. The mechanism responsible for elevated temperature deformation has also been discussed.