A Study on Ni-Fe Ball Milled Spark Plasma Sintered Sample

Abstract

Mechanical alloying through high energy ball milling was used to produce 40wt.%Ni-Fe alloy powder of average particle sizes 80 μm and 25 μm respectively. High Energy Planetary ball milling at room temperature was performed for various time durations of 16, 32 and 64 hours. Sintering was carried on DR.SINTER.LABTM (SPS 515S) machine. Samples were sintered at constant temperature of 650°C and pressure of 30 MPa for all samples. This study exhibits in same alloy, but increases of milling hours, the densification of the sintered samples decreases and also porosity of the sample increases. This may be due to the reasons of increases in the surface area of the milled nanopowder (ie. Reduction of particle size), low green body density of long milling powders by agglomeration of powders and oxidation of powders during a milling process. However, this study revealed that in the same alloy with increasing milling hours, required more temperature and pressure for perfect densification. Densification of 85.4 % was achieved in 16 hours milled sample.