The effect of Cu-macroalloying on β-NiAl intermetallic compound obtained by mechanical alloying

The synthesis and bending strength of nanocrystalline β-phase NiAl intermetallic compound macroalloyed with copper are discussed in this paper. Nanocrystalline NiCuAl powders were prepared by mechanical alloying of elemental Ni, Al and Cu powders under argon atmosphere. The alloyed nanocrystalline powders were consolidated by double action pressing at a pressure of 1.20 GPa and sintered at 1000 °C during 20 min to 80% dense compacts. X-ray diffraction patterns show that 40 min was enough to transform Ni, Cu and Al elemental powders into NiAl intermetallic compound. The crystallite size measurements revealed that the grain size of the NiCuAl phase decreased from 8.5 to 5.4 nm with increasing mechanical alloying time from 40 to 240 min. Bending strength shows an increment as the copper content is raised up to 7.5 at.%. After this point bending strength values decrease. The modulus of elasticity shows the same behavior as the bending strength.