Effect of Cu additions over the lattice parameter and hardness of the NiAl intermetallic compound

A set of NiAl intermetallic alloys was prepared with several Cu additions, exploring the Ni-rich and the Al-rich side of the NiAl intermetallic compound. An abrupt increment in hardness was obtained in the Al-rich alloys, while the opposite occurs in the Ni-rich alloys. This may be due to the presence of β-phase (Ni,Cu) Al and γ′-phase (Ni,Cu)3Al, in addition to the variation of the β-phase lattice parameter.