Synthesis and characterization of tri-aluminide in situ composites

Abstract

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.