Laser deposition of a Cu-based metallic glass powder on a Zr-based glass substrate

Laser Engineered Net Shaping (LENS™) is a laser-assisted manufacturing process that offers the possibility of producing metallic coatings and components with highly nonequilibrium microstructures. In this work, the microstructure developed by LENS deposition of Cu₄₇Ti₃₃Zr₁₁Ni₈Si₁ powder on a bulk metallic glass substrate, with nominal composition Zr_58.5Nb_2.8Cu_15.6Ni_12.8Al_10.3, is investigated. Single-layer deposition results in the formation of an inhomogeneous but partially amorphous layer above a crystalline heat-affected zone. Elemental analysis of the deposited layer indicates incomplete mixing of the powder with the melt pool. The as-deposited alloy exhibits a single glass transition event and its primary crystallization event is consistent with the first crystallization temperature of the Cu-based powder. Subsequent remelting of this layer results in a still partially amorphous deposit with a uniform composition of (Zr + Nb)_51.8Cu_24.7Ti_3.4Ni_16.4Al_3.7. The remelted layer exhibits a structural rearrangement immediately prior to the primary crystallization event, possibly associated with the formation of a quasicrystalline phase.