A study on factors affecting the densification ofspark plasma sintered ball milled 40 wt% Ni-Fe nanopowder

Abstract

Using High Energy ball milling, the particle size of average 80 µm and 25 µm, 40 wt% Ni-Fe alloy powder was produced by mechanical alloying respectively. For different time intervals of 16, 32 and 64 hrs, at room temperature, high energy planetary ball milling was done. On “DR.SINTER.LABTM (SPS 5155) machine” spark plasma sintering (SPS) was performed. At constant temperature and pressure of 650 °C and 30Mpa respectively, all samples were sintered. The research is applied on same alloy, as milling hour increases, porosity increases and densification decreases of the samples, this is because of some reasons that are “increase in the surface area of the milled nanopowder (i.e. Reduction of particle size), low green body density of long milling powders by agglomeration of powders and oxidation of powders during a milling process”. As milling hour increases, for perfect densification, more temperature and pressure is needed. In 16 h of milling 85.4% densification was achieved.