Effects of pore diameter and B2–NiTi crystal on plasticity of amorphous Ni–Ti alloy based on molecular dynamics simulation

Abstract

The poor plasticity of metallic glasses (MGs) limits its applicability as engineering materials. Therefore, it is particularly important to find ways to improve the plasticity of metallic glasses. In this study, the effects of pore diameter and B2–NiTi crystal on the compressive deformation of Ni50Ti50 MGs are studied by molecular dynamics simulation. The results demonstrate that pores effectively inhibit rapidly stress reduction. Pore experiences pressure in the direction of the load under compression process, which induce the formation of high shear strain atoms around the pores. The presence of pore induces the formation of shear transition zones (STZs) and shear bands. Specifically, larger pore diameters result in lower yield strengths, flatter stress-strain curves, and increase plasticity of MGs. As the B2–NiTi crystal is highly resilient in MGs, it could not be easily destroyed. In the compression process, the B2–NiTi crystal reduce the deformation of the system and impede the propagation of shear bands. As a result, the shear bands only propagate in the cracks of crystals. The larger number of crystals lead to a larger inelastic deformation interval in the nanocomposites and improve the ability to block the propagation of shear bands. These findings elucidate the relationship between yield strength, shear band, plasticity, pore diameter, and B2-phase crystals, and provide theoretical guidance for the development of MGs with improved plasticity.

Keywords

• Ni–Ti amorphous
• Pore diameter
• B2–NiTi crystal
• Shear band
• Plasticity