The effect of Cu addition on the morphological, structural and mechanical characteristics of nanocrystalline NiTi shape memory alloys

Abstract

An attempt has been made to develop the nanostructured NiTi and NiTiCu shape memory alloys (SMAs) using mechanical milling method. The effects of milling and the addition of Cu as ternary element in NiTi SMA was analysed by evaluating its structural and morphological characteristics. Experimental results obtained from the XRD phase analysis, crystalline nature, crystallite size and lattice strain of the synthesized monocrystalline elements, confirmed the formation of B2 phase-intermetallics such as NiTiCu and NiTi. The microstructural characteristics and formation of agglomerates in case of NiTi and NiTiCu system can be altered by increasing the milling time. The results suggest that the use of mechanical synthesis for NiTi based shape memory alloys stimulates the formation of solid phase homogeneous nanocrystalline elements. Addition of Cu in NiTi resulted in the formation of nanocrystalline with a size of ∼23 nm. The diffraction patterns of nanocrystalline NiTi SMAs were characterized with diffraction rings and reduction in lattice parameter.