Effect Of Al+B4C Agglomerate Size On Mechanical Properties Of Trimodal Aluminum Metal Matrix Composites

Trimodal aluminum (Al) metal matrix composites (MMCs) consisting of a nanocrystalline Al (ncAl) phase, B4C reinforcement particles, and a coarse grain Al (cgAl) phase contain multiscale microstructure and interfacial features that contribute to exceptional mechanical properties. One of the hierarchal microstructural features within the composite, namely the ncAl+B4C agglomerates formed during cryomilling, is an important feature whose size can range from tens of micro-meters to millimeters. This paper reports a study on the influence of the ncAl+B4C agglomerate size on the dynamic compressive strength of the trimodal Al MMCs. A desired hierarchal microstructure for high-strength of Al MMCs is identified to contain uniformly distributed relatively small ncAl+B4C agglomerates. Commercial-scale fabrication process to achieve this microstructure includes size classification by sieving the cryomilled ncAl+B4C agglomerates