Tensile properties and deformation micromechanism of Ti-based metallic glass composite containing impurity elements

To study the tensile deformation behavior and deformation micromechanism of Ti-based bulk metallic glass composites (BMGCs) containing high levels of impurity elements, 2 at.% nitrogen or oxygen was introduced into a BMGC with a nominal composition of Ti₄₈Zr₂₀Nb₁₂Cu₅Be₁₅. The solid solution strengthening caused by solute atoms and embrittlement due to excess oxygen were examined in detail using transmission electron microscopy observation and theoretical analysis. Special attention was paid to changes occurring at the interface in order to propose a more microscopic interpretation of macroscopic and micron-scale phenomena, such as the two-phase coordinated deformation behavior in the work-hardening stage of the low-tensile plastic composite and the brittle failure mechanism resulting from excessive oxygen content. A precipitation phase of nanoscale polycrystals distributed at the interface was found in the composite with 2 at.% oxygen. The appearance of these harder precipitated polycrystals is conducive to microcrack generation but cannot stop microcrack growth, so it has disastrous effects on the properties of the materials. Adding appropriate solute atoms to Ti-based BMGCs at a suitable dose can be an inexpensive and convenient method of adjusting the mechanical properties in a wide range. This work can provide suggestions for optimizing the impurity element content and preventing embrittlement considering macroscopic and microscopic features.