Atomic study on deformation behaviors of crystal-glass nanocomposite with a typical hierarchical structure

The deformation behaviors of crystal-glass nanocomposites with structural heterogeneities that contain different grain sizes in their crystal phase are studied by using molecular dynamics simulation. Their stress-strain response and microstructures evolved with the applied tensile strain are quantitively analyzed. It is found that the mechanical response of the nanocomposite is sensitive to the average grain size of its crystal phase, and the specimen with the smallest grain size exhibits the highest strength among all. Strain partitioning inevitably occurs between the crystal phase and the glassy domains during the tensile loading, while the average atomic shear strain of the glassy phase is increased with the grain size of the crystal phase. As well, the increased grain size also aggravates the strain localization inside the glassy domains, which promotes the formation of shear transformation zones (STZs) and facilitates the strain heterogeneities there. A mass of lath-like stain paths with severe strain localization are also observed to form in the nanocomposite specimen with a larger grain size, which can function as the transmission medium for delivering the shear strains between different domains and accommodating the plastic flows during the deformation. The present work is aimed to underline that the configuration of structural heterogeneities in the glass-crystal nanocomposite can alter the strain partitioning between different phase domains, which can be used to tune the mechanical performance of the nanocomposite. The unveiled atomistic deformation mechanism of the crystal-glass nanocomposite also provide new sights on designing and optimizing the structural heterogeneities of nanocomposites for achieving better mechanical properties in future.