Laser Additive Manufacturing of Layered Zr-Based Bulk Metallic Glass Composite

Abstract

As a potential functional material, much effort has been devoted to enhancing the mechanical properties of bulk metallic glass composites (BMGCs). Among them, layered BMGCs are regarded as effective for achieving a strength–ductility synergistic effect. However, it is difficult with the existing metallic glass (MG) preparation technologies to obtain a decent layered structure. In addition, the fragile interface between layers formed using the traditional fabricating method always exacerbates the deterioration of mechanical properties, which restricts the wide application of layered BMGCs. In the case of laser additive manufacturing (LAM), the cooperation of coarse grains in the hot affected zone (HAZ) and fine grains in the remelting zone induced by a unique thermal history is of key importance in eliminating the fragile interface and therefore overcoming premature cracking. Thus, we successfully synthesized Nb-Zr48Cu46.5Al4Nb1.5 layered material with a yield strength of 1332 (±91) MPa and a compression ductility of 4.17 (±0.14)% via LAM. The results of the compressive curves of Nb and BMGC prepared by LAM decisively demonstrate that the layered material obtains a certain degree of plasticity while maintaining relatively high strength. This remarkable mechanical property is mainly attributed to the asynchronous deformation and the interaction of the adjacent Nb and MG layers. It is worth emphasizing that a distinctive round-way crack extension is discovered during the deformation process, which plays a significant role in breaking through the strength ductility trade-off. In addition, the source of yield strength is calculated theoretically using the rule of the mixture and the dislocation strengthening principle. The results indicate that the strength contributed by geometrically necessary dislocations is around 101.7 MPa. In addition, the strength calculated by the rule of the mixture is ~1201.9 MPa. This work offers a new paradigm for BMGCs with excellent strength and ductility as practical engineering materials.