Study the effect of milling parameters on HE-MA nanostructured Al6061-graphene cermet feedstock particles

The paper presents research work pertaining the synthesis of high-strength nanostructured ceramic-metallic (cermet) particles in a high-energy mechanical alloying (HE-MA) method based on Al6061-graphene composite system. The goal was to optimize the milling process parameters, namely milling time, ball-to-powder (BPR) ratio, and ball diameter following a rigorous material batch design protocol. The milled products were characterized using SEM, XRD, and laser particle diffractometer to study the morphology and microstructure, elemental composition, grain size and crystal orientation, and particle size distribution (PSD) at pre-determined time intervals. Results show good conformance between experimental results and analytical estimates concerning Al6061 crystal size reduction, microstrain formation, and graphene reinforcement orientation and embedment over the milling duration, leading to achieving >80% volume fraction of particles in 10–160 μm size range. Finally, it was possible to achieve particle size, morphology, and PSD with 5-mm-diameter ball, 10:1 BPR, and 4 h of milling with 66% (by volume) particles lying in the 8–45 μm range, suitable as feedstock for cold spray deposition.