Development of TiB2 reinforced aluminum foundry alloy based in situ composites – Part I: An improved halide salt route to fabricate Al–5 wt%TiB2 master composite

In Part I of the two part study, an improved halide salt route was developed to fabricate in situ TiB2 particulate reinforced aluminum matrix master composites based on the well-established flux assisted synthesis (FAS) method using mechanical stirring. By microstructural and element-recovery analysis, we show how the simple but effective “improved method” – leaving the reactant molten salt on the surface of aluminum melt without introducing any stirring during holding – influences the mechanical performance of the final composites. Processing parameters in terms of holding duration, reaction temperature and stirring speed before casting were optimized to produce Al–5 wt% TiB2 composite with consistent and sound quality. The experimental Al–5TiB2 composite, prepared under the improved halide salt route condition, has achieved a 140% improvement in the UTS without compromising its ductility with respect to the Al matrix. The experimental validation of using the developed Al–5TiB2 composite as a master composite to reinforce aluminum foundry alloys will be presented in Part II.