Laser glazing of a quasicrystal-reinforced Al-Cu-Fe-Cr alloy: Implications for use in additive manufacturing

Quasicrystal-reinforced aluminum metal matrix composites exhibit combinations of properties that are attractive for metal additive manufacturing. It is challenging to evaluate such systems due to difficulties in modeling the solidification and microstructural evolution. Here, laser glazing in a powder bed fusion instrument was used as an efficient method to evaluate an Al85Cu6Fe3Cr6 alloy, and the resulting microstructures were characterized using electron microscopy. The arc-melted alloy contained only crystalline phases, but pre-glazing of the surface gave a refined microstructure comprising I-phase quasicrystals, Al2Cu and FCC Al. Individual laser tracks produced in this layer under different conditions exhibited an extremely fine and uniform phase mixture with over 70% by volume of I-phase in a FCC Al matrix with a thin film of Al2Cu at the interface, and no cracking or macrosegregation. The reasons for the formation of I-phase, rather than the D-phase that has been reported previously in this alloy, are discussed.