Formation of metallic glass coatings via laser deposition

Metallic glasses have attracted tremendous attention as structural materials because of their remarkable mechanical and corrosion properties. Laser deposition is a useful technique to create and produce coatings with amorphous or uniquely tailored, non-equilibrium microstructures. In this study, we use the Laser Engineered Net Shaping (LENS^TM) process to deposit pre-alloyed Zr-based and Cu-based metallic glass forming powder on the Zr-based glassy substrates. In both cases, amorphous melt zones are observed surrounded by crystalline heat-affected zones (HAZs). The microstructures of the deposited materials and underlying substrates were analyzed and characterized as functions of the laser processing parameters. To better understand the thermal environment for the formation of metallic glass coatings via laser deposition, a three-dimensional finite element model was performed and compared with the in-situ thermal imaging measurements. It is indicated that optimization of the laser energy input can result in the formation of a continuous amorphous layer with the elimination of underlying crystalline HAZs.