Construction of metallic glass structures by laser-foil-printing technology

Metallic glasses (MGs) have superior mechanical properties such as high tensile strength, hardness, and corrosion resistance, as compared to crystalline metals. Although newly developed MGs have significantly reduced critical cooling rates down to 10 K/s, products of MGs are still limited to simple geometries such as foils/plates or rods with thin section-thickness which is mainly caused by the decrease of thermal conductivities of the new MGs. Recently, we developed a new Laser-foil-printing (LFP) additive manufacturing technology which welds foils, layer by layer, to construct desired 3D structures. With the LFP and Zr-based amorphous foils, 3D, large amorphous structures with complex geometry have been successfully manufactured. To better understand the evolution of crystalline phase, we integrate the finite element based heat transfer model and classic nucleation theory (CNT) based crystal nucleation/growth model. The model was used to demonstrate the evolution of crystal phase as a function of time during laser welding at different locations including the fusion zone (FZ) and heat-affected zone (HAZ). The model is also compared favorably with the experiment results. The reported susceptibility to crystallization in HAZ were discussed and explained.