Production of Nanostructural NiTi Shape Memory Compound via Mechanical Alloying Process |
Paper ID : 1519-UFGNSM-FULL |
Authors: |
ashkan zolriasatein1, Hamidreza Rostami2 1Advanced Materials and Nanotechnology Research Center, Faculty of Mechanical Engineering,
K.N. Toosi University of Technology 2Faculty of Materials Engineering, Science & Research Branch, Islamic Azad University |
Abstract: |
Due to unique shape memory and superelasticity behavior, NiTi shape memory compound has attracted attentions in many applications such as medical, automotive and aerospace industries. In this research, nanocrystalline NiTi powder (with equal atomic percentage) has been produced by mechanical alloying (MA) method. MA process was chosen because of Cost saving, ease of use and creating nano-structured compositions. High purity initial elemental powders were mixed with employing stearic acid as the process control agent (PCA) under argon atmosphere in a hardened steel container. The effect of milling time on the grain size and microstrain of samples was studied. The grain size and microstrain was calculated by XRD patterns and Williamson-Hall formula. The X-ray diffraction (XRD) analysis indicated that formation of intermettalic NiTi with crystallite size of 22 nm after 60 h of ball milling. In order to investigate the morphology of powders at various MA times, the microstructure of fabricated samples was studied with scanning electron microscopy (SEM) and illustrated homogeneous distribution of formed phases with globular-structure. Annealing of as-milled powders at 1173 K for 900 s leads to formation of nanometric NiTi (B19΄), Ti2Ni and Ni3Ti phases. |
Keywords: |
Mechanical Alloying; Nanostructural; NiTi; Shape Memory. |
Status : Paper Accepted (Poster Presentation) |