Solid-state transformation in ball milled nickel powder

A solid-state tetragonal transformation of ball milled and cold pressed unmilled nickel powder is proposed. The phase evolution was characterized using the X-ray diffraction (XRD) technique, while the phase transition was analysed by the differential scanning calorimetry (DSC). However, the lattice parameters obtained on the surface of the cold pressed sample are smaller than the lattice parameters of the 2 h ball milled powder. Crystallization of two exothermic peaks was observed during DSC analysis of the milled powder, which was not the case in cold pressed powder.