Processing effects on the characteristics of the in-situ formed Al3Ni reinforcement in a PM Al matrix

The aluminides capability to be synthesized from the elemental metallic powders through an exothermal reaction (Reactive Synthesis) was used to produce in-situ reinforced Al/20vol%Al3Ni composites. With this powder metallurgy approach, due to the exothermal character of the reaction the processing temperatures cm be lowered and cleaner matrix/reinforcement interfaces obtained. Uniaxial or Cold lsostatic Pressed preforms of Al and Ni powder blends were furnace reacted during vacuum and inert atmosphere sintering cycles Reactive Sintering (RS); a pressure-assisted reactive sintering route - Reactive Hot Isostatic Pressing, was also used. Densification, microstructural characterization (reinforcement homogeneity, morphology and distribution) and Young's modulus of the composites as well as HV microhardness measurements of formed Al3Ni are correlated with the composites processing. The obtained results indicate that in RS of Al/20vol%Al3Ni, the samples heat release can be controlled through an appropriate choice of furnace atmosphere and surface-to-volume ratio of the preforms, allowing the fabrication of near-net-shapes by this more cost-effective route.