Nanoindentation, Compressive and Tensile Deformation Study of In-Situ Al-AlN Metal Matrix Composites

In-situ formation of ceramic particulate as a reinforcement in Al matrix results in superior mechanical properties of synthesized Al based composites. Resulting composites are thermodynamically stable with clean particulates having strong bonding with matrix. In the present study, Al melt held at 700 A degrees C is nitrogenated using NH4Cl + CaO as a nitriding precursor to form ultrafine AlN particulates in melt. Nanoindentation, tensile and compressive tests are conducted on the synthesized composite to evaluate its deformation behavior. The load bearing capacity of ultrafine sized, well bonded in-situ AlN particulate with Al matrix show a prominent improvement in nanoindentation hardness, compressive, and tensile strength of composites. In comparison to monolithic Al, composites reveal increase in yield strength to an extent of 60-96 % and 88-100 % under compressive and tensile loads respectively. Nanoindentation results of the composites also exhibit higher hardness and modulus of elasticity in range of 11-16 % and 16-34 % respectively in comparison to pure Al matrix.