Enhancement of plasticity and toughness of 3D printed binary Zr50Cu50 bulk metallic glass composite by deformation-induced martensitic transformation

3D printing based on selective laser melting (SLM) provides a new route to fabricate bulk metallic glass (BMG) components with desirable geometries. However, repeated laser scanning induced partial crystallization in heat affected zones (HAZs) in the 3D printing process leads to a deterioration in plasticity and fracture toughness of the printed BMGs. Here, we applied the SLM technique to fabricate a Zr50Cu50 bulk metallic glass composite reinforced with in situ-generated B2 austenite in HAZs, where the B2 phase could transform to B19' martensite during deformation and enhance the ductility due to the transformation-induced plasticity (TRIP) effect. In addition, the B2 phase in HAZs and the amorphous phase in molten pools form a so-called "brick-and-mortar" structure, which effectively blocks crack propagation, thus improving the fracture toughness. The present work provides a new avenue for the fabrication of large-sized bulk metallic glass composites by SLM with outstanding mechanical properties. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.