Effects of characteristics of Mo dispersions on the plasticity of Mg-based bulk metallic glass composites

The Mg58Cu28.5Gd11Ag2.5 bulk metallic glass composites (BMGCs) dispersion strengthened by porous Mo particles with different volume fractions and particle sizes were synthesized by casting and characterized. The presence of porous Mo particles could restrict the shear band propagation. It was found for a given volume fraction of Mo particles, smaller particles would lead to more interfacial areas, shorter inter-particle free spacings, smaller confinement zone sizes than the larger particles, and consequently the improvement of compression plasticity from 10% up to 27%. Also, for a given Mo particle size, higher volume fraction would lead to larger compression plasticity. The inter-particle free spacing, as well as the confinement zone size (mean free path of shear bands), appears to be the controlling factor in limiting the propagation of shear bands which in turn affecting the plasticity of BMGCs.

Compressive true stress–strain curves of the Mg58Cu28.5Gd11Ag2.5 BMGC rods with different vol.% of 20 ± 4 μm Mo particles. Insert: image of plastic deformed and fracture sample.Figure optionsDownload as PowerPoint slideResearch highlights
► We found that shear bands are often arrested by the amorphous matrix-Mo interfaces in these Mg-based BMGCs.
► The traveling distance, i.e. mean free path, of shear bands is drastically limited by the inter-particle free spacing of Mo particles.
► Both the failure strain and fracture toughness exhibit a similar increasing trend with decreasing mean free path.
► It is apparent that the mean free path plays an important and controlling role on the toughening of the Mg-based metallic glasses.