Effect of electron concentration on the Laves phase stability of NbCr₂–Ni produced by powder metallurgy

The powder metallurgy technology of mechanical alloying followed by hot-pressing consolidation has been used to obtain NbCr2–Ni Laves phases. High-purity Nb, Cr, and Ni crystalline powders were milled for periods up to 35 h. These powders were vacuum sintered at 1250°C for 0.5 h under 45 MPa. The phase transformations of NbCr2–Ni Laves phases have been investigated by X-ray diffraction. The grain size decreases and the microstrain increases with increased Ni content. Different phase transformations were observed from NbCr2–Ni intermetallics. It is found that the electron concentration and phase stability correlation is obeyed in the Nb–Cr–Ni systems. However, the electron concentration corresponding to the C15/C14 phase transition is found to move to a higher value (i.e. 6.103) than the predicted one (i.e. 5.88) in the literature.