Microstructure and mechanical behavior of polymer-derived in-situ ceramic reinforced lightweight aluminum matrix composite

Metal/alloy matrices have been previously reinforced with ceramic nanoparticles, but such reinforcements tend to agglomerate, have weak interfaces, and are expensive. Polymer-derived ceramics (PDCs) based composites can potentially overcome these shortcomings. These composites are obtained from the preceramic polymers after pyrolysis. These polymers are inexpensive, can be fragmented to the nanoscale, and pyrolyzed in-situ. Friction stir processing (FSP) was used to fragment and disperse the polymer within an Al-Mg alloy. The PDC particles pinned the dislocations and grain boundaries. The composite exhibited a microstructure resulting from dynamic recrystallization with an average grain size of ~1 µm. It also exhibited both high strength (96% and 24% improvement in the yield and tensile strength, respectively) and good ductility. Interestingly, the serrations in the tensile curves commonly observed in Al-Mg alloys due to the Portevin-Le Chatelier (PLC) effect was reduced in the composite. •Al matrix composite reinforced with in-situ formed polymer-derived ceramic was fabricated using friction stir processing.•It exhibited high strength (96% and 24% improvement in the yield and tensile strength, respectively) and good ductility.•The amplitude of the serrations in the tensile curve due to the Portevin-Le Chatelier effect was reduced in this composite.