Effect of Two-Step Ball Milling on Microstructure and Mechanical Properties of Al4032/Bimodal-B4C Composites

Al4032/Bimodal-B4C composites were synthesized via different milling methods, namely low speed ball milling (SLBM), high speed ball milling (SHBM) and two speed ball milling (TSBM). The Al4032 powder particles were shifted to flakes and some agglomerated B4C were slowly dispersed in flakes during SLBM. SHBM generated severe cold welding of Al4032 flakes and stronger collision, resulting in agglomerated zones within the Al matrix grain. While, TSBM processed samples showed the well coordination of bimodal B4C dispersion in matrix material and better interfacial bonding between Al4032/B4C. The composite powders synthesized at varying concentration of B4C (2.5, 5 and 7.5 wt.