Fracture toughness and destructive mechanism of ductile nanoporous metallic glass and its crystal-impregnated nanocomposite

YH Zhang and JF Xu and YQ Hu and L Su and SH Ding and WW Wu and R Xia, SCIENCE CHINA-TECHNOLOGICAL SCIENCES, 66, 3328-3342 (2023).

DOI: 10.1007/s11431-022-2313-4

Nanoporous metallic glasses (NPMGs) and crystalline/amorphous nanocomposites exhibit superior ductility over bulk macroscopic metallic glasses (MGs). Their fracture behaviors remain a mystery due to experimental technical limitations. In this work, the fracture behaviors of pre-cracked NPMGs and crystal-impregnated nanoporous metallic glasses (CINPMGs) are investigated through large-scale molecular dynamics simulations, and the MG and crystal phases are amorphous Cu50Zr50 and crystalline B2 CuZr, respectively. Fracture toughness is determined by simultaneously considering the surface energy and plastic dissipated energy. Our results confirm the excellent plasticity of both the pre- cracked NPMGs and CINPMGs. The progressive necking and ductile rupture of ligaments are responsible for generating NPMGs with prominent ductility and fracture toughness. Meanwhile, secondary cracking is also triggered, which can consume energy without extending the major crack, thus further improving fracture resistance. It is also found that the fracture toughness of NPMGs can be improved by increasing the solid fraction of MG, and linear relation between fracture toughness and solid fraction can be expected. Crystal impregnation effectively inhibits global failure as the crystal phase shields the individual amorphous ligaments. Homogeneous plastic flow characterized by shear bands is observed in CINPMGs, and this homogeneous global deformation is facilitated by the crystalline/amorphous interface. Besides, the fracture toughness of CINPMGs is higher than that of the constituent single phases, regardless of the volume fraction of each phase. Ashby material charts manifest that these two types of materials demonstrate promising potential in the material selection library for advanced structural design.

Return to Publications page