The Effect of the Processing Parameters on the Properties of the Liquid Phase Spark Plasma Sintered 80Fe-20(Al + MWCNT) Magnetic Metal Matrix Nanocomposites

In this paper, the liquid phase sintering was performed using spark plasma sintering to produce iron (Fe: 80 vol%)-aluminum (Al)-multi-walled carbon nanotubes (MWCNTs) magnetic hybrid metal matrix nanocomposites. The properties of the nanocomposites were investigated by considering different parameters of materials processing. The reinforcement of MWCNT with a content of 0-2 vol% did not affect the saturation magnetization of the nanocomposites but increased the coercivity and reduced both the electrical resistivity and the mechanical transverse rupture strength. It was found that milling the powders for 24 h resulted in composite with high saturation magnetization (148.820 A center dot m(2)/kg) and high coercivity (2175.6 A/m) but further milling time had reduced the values of magnetic properties. The mixture of Fe nanoparticles and Fe microparticles in composites with a nanoparticles-to-microparticles volume ratio of 1:1 has led to the enhanced saturation magnetization up to 157.820 A center dot m(2)/kg and reduced the coercivity of 50.20% in comparison with the Fe nanoparticles based nanocomposites. That mixture exhibited good electrical resistivity but caused the reduction of mechanical strength. The post-sintering annealing has significantly improved the magnetic softness of the composites by reducing the coercivity up to 854.30 A/m and increased the saturation magnetization.