Electron energy-loss spectroscopy study of NiTi shape memory alloys

Electron energy loss spectroscopy (EELS) investigations were carried out on NiTi shape memory alloys. The composition of lens-shaped precipitates is determined to be Ni4Ti3 by model-based EELS quantification, and the Ni-depleted zone in the B2 matrix surrounding the Ni4Ti3 precipitates was quantified. The Young's modulus Ym of the B2 matrix with 51 at.% Ni and the Ni4Ti3 precipitates was evaluated to be about 124 and 175 GPa, respectively. The intensity of the Ni L3 edge for the precipitate is slightly higher than that for the B2 phase.