Thermal analysis on the curie temperature of nanocrystalline Ni produced by ball milling

Ball milling on Ni powder at 2, 4, and 6 h interval resulted in a decrease in crystalline sizes of 35, 17 and 13 nm, respectively. Thermal analysis was carried out on unmilled and milled Ni powders. Differential scanning calorimetry curves of milled powder indicated the shifting of magnetic transition temperature peak to lower values whereas thermo-gavimetric curves revealed higher weight loss during heating which confirmed Ni volume expansion on becoming paramagnetic. However, at high temperature the ferromagnetic suppression induced by mechanical milling is lost, hence the normal Curie temperature is restored due to possible grain growth.