Synthesis and structural properties of Ni–20Cr–2Y2O3 nanocomposite alloy prepared by a very high energy mechanical milling

Ni–20Cr–2Y2O3 nanocomposite alloys were synthesized by a very high energy ball milling (applied milling energy, ∼180 kJ g−1 hit; milling speed, ∼1000 rpm) using the coarse yttria (Y2O3; ∼50 μm) starting powders, and their formation behavior was investigated with particular attention paid to Y2O3 particles. Homogeneous Ni–20Cr–2Y2O3 nanocomposite alloy powders were achieved in a short milling time of 40 min; the Cr elements were almost fully alloyed into the Ni lattice, and simultaneously the original coarse cubic Y2O3 particles were transformed into extremely fine monoclinic nanocrystals. Thermal consolidation by spark plasma sintering induced homogeneous precipitations of the Y–Cr–O nano-clustered oxides (mean diameter dm ∼12 nm), which were identified as an orthorhombic YCrO3 structure (space group Pnma, a = 0.5523 nm).