Microstructures and mechanical properties of nanocrystalline NiTi intermetallics formed by mechanosynthesis

The formulation of nanocrystalline NiTi shape memory alloys has potential effects in mechanical stimulation and medical im-plantology. The present work elucidates the effect of milling time on the product's structural characteristics, chemical composition, and mi-crohardness for NiTi synthesized by mechanical alloying for different milling durations. Increasing the milling duration led to the formation of a nanocrystalline NiTi intermetallic at a higher level. The formation of nanocrystalline materials was directed through cold fusion, fractur-ing, and the development of a steady state, which were influenced by the accumulation of strain energy. In the morphological study, uninter-rupted cold diffusion and fracturing were visualized using transmission electron microscopy. Particle size analysis revealed that the mean particle size was reduced to ~93 μm after 20 h of milling. The mechanical strength was enhanced by the formation of a nanocrystalline in-termetallic phase at longer milling time, which was confirmed by the results of Vickers hardness analyses.