Development of in-situ porous Ti particle reinforced Mg-Cu-Gd metallic glass matrix composite with dual-scale reinforcing structures

• In-situ porous Ti particles are introduced into Mg-based BMG via dealloying in metallic melt. • Various volume fractions and sizes of in-situ porous Ti are introduced. • Composites show both higher strength and better plasticity with more finer particles. • Modified rule of mixture is proposed to predict the yield strength of the composite. • Dual-scale reinforcing structure contributes to the strength-plasticity synergy. In the present work, the porous Ti particle reinforced Mg-based bulk metallic glass matrix composites (BMGCs) have been successfully fabricated via a novel in-situ dealloying method in metallic melt. A dual reinforcing structure, including large-scale between porous particles and fine-scale inside one particle, was induced to further overcome the strength-plasticity tradeoff. The microstructure and mechanical properties of such dual-scale structure-reinforced BMGCs with various volume fractions and diameters of porous Ti particles were investigated in detail. It is found that with more and finer porous Ti particles, the BMGC showed both high fracture strength (1131.9 ± 39.1 MPa) and good plastic deformability (1.48 ± 0.38 %). The characteristic of the reinforcing structure (0.48 µm) inside the porous particles was close to the plastic processing zone size of the matrix (0.1∼0.2 µm), which generated a locally ideal reinforcing structure. Such dual-scale reinforcing structures with more interfaces can effectively promote the multiplication of shear bands at the interfaces. Due to the size effect, the refined submicron matrix between the Ti ligaments inside the porous particles should exhibit homogeneous shearing events. Such delocalization behavior from the dual-scale reinforcing structures should help to enhance the role of the interactions between shear bands, thus improving the yield strength of the composites. Based on the in-situ dealloying method, the dual-scale structure design provides a novel approach to fabricate various BMGCs with both high strength and good plasticity.