The enhancement of tensile strength and elongation in two phase (NiAl+Ni3Al) intermetallics of Zr-doped Ni–20Al–27.5Fe (at.%) alloys

Microstructure and tensile properties in the nickel intermetallics, Ni–20Al–27.5Fe and Ni–20Al–27.5Fe–1Ti (at.%), were investigated in order to understand the effect of zirconium addition. It was found that the addition of zirconium causes formation of a thin layer along the phase boundary of NiAl and Ni3Al. The thin layer was identified as an ordered fcc phase with 6.9 Å in lattice parameter. The compressive deformation caused by hot extrusion results in fine precipitates and a mixture of subgrains within the matrix phase in zirconium-doped alloy. Additional zirconium gives significant improvement in the room and high temperature fracture strength and strain. The extruded zirconium-doped alloy exhibited a high tensile elongation of above 10%, and also a relatively high tensile strength of 1350 Mpa at room temperature, keeping it as high as 600 Mpa at 700°C.