Synthesis and characterization of tri-aluminide in situ composites

AA5052 tri-aluminide in situ composites with different vol.% of Al₃Zr particles were produced by direct melt reaction in situ technique. The in situ composites were characterized by differential thermal analysis for reaction temperature and X-ray diffractometer for phase analysis. Optical, scanning, and transmission electron microscopy were conducted for morphology and distribution of particles. These studies showed grain refinement of matrix with second phase particles, different morphologies of Al₃Zr, and their uniform distribution with particle size range. The presence of dislocations was also observed in TEM studies which contribute to hardness and strength of composites. Composite with 10 vol.% of Al₃Zr showed maximum strength and toughness while hardness continuously increased up to 30 vol.% Al₃Zr. The cumulative mass loss increased with sliding distance, whereas coefficient of friction (COF) showed a fluctuating tendency. Wear rate continuously increased with load while COF showed a decreasing trend. For base alloy and composite with l0 vol.% Al₃Zr, wear rate decreases up to 3 m/s sliding velocity and beyond this value a sharp increase in wear rate is observed, whereas composites with higher vol.% of Al₃Zr show increasing trend of wear rate from beginning but at much lower rate. COF shows an increasing trend with sliding velocity for all compositions. Wear rate and normalized wear rate continuously decrease with an increase in vol.% of Al₃Zr particles while COF shows an increasing trend. All these results have been correlated with roughness (Ra) values and worn surfaces studies.