Evolution of Nano-structured Products in Mechanical Alloying of Ni and Ti with or w ithout Process Control Agent

摘要

Mechanical alloying technique was employed to produce nano-structured NiTi compound using elemental mixture with equiatomic composition. Also, addition of 2% process control agent (stearic acid, methanol or ethanol) was examined. A relatively fast reaction was found between Ni and Ti in the absence of PCAs and formation of B2-NiTi nano-crystallites were detected using XRD and TEM after 30h of milling. The mean particle and crystallite size were ~2μm and –30nm, respectively. Using ethanol, methanol or stearic acid as PCA, resulted in the reduction of the milled products to –90nm (exhibited by SEM), but no NiTi phase formed. Instead the milled products were found to be contaminated by oxygen.