Use of laser glazing to evaluate an Al-Cr-Co-Mn-Zr alloy containing icosahedral quasicrystalline dispersoids as a candidate material for additive manufacturing

Abstract

Evaluating novel alloy systems for metal additive manufacturing (MAM) is challenging especially when metastable phases are involved. Here, laser glazing was used as a cost-effective method to evaluate the potential of a powder-processed Al-Cr-Mn-Co-Zr alloy for MAM. The alloy powder exhibited a nano-composite microstructure consisting of an FCC Al matrix plus icosahedral quasicrystal (I-phase) dispersoids, and this microstructure was retained in the as-consolidated alloy. Single laser tracks were produced on the surface of a polished coupon of the consolidated alloy at a range of laser powers and scan speeds in a commercial powder bed fusion (PBF) system. The resultant microstructures and mechanical properties of the laser tracks were investigated by electron microscopy studies and hardness measurements. The laser tracks showed no solidification cracking, and the only morphological defects were occasional pores. All of the phases in the substrate alloy were melted fully in the laser tracks, and four different types of microstructures (solid solution, equiaxed dispersoids, mixed and radial growths) were observed in the solidified tracks. The microstructures obtained depended upon the input energy densities due to the combinations of laser processing parameters. The laser tracks with the solid solution and equiaxed dispersoid microstructures gave the highest hardness values of 154–170 HV, which is comparable to that of the substrate alloy. These data indicate that there is considerable promise for the application of such I-phase alloys in MAM.