Composition gradients surrounding Ni_4Ti_3 precipitates in a NiTi alloy studied by EELS, EFTEM and EDX

Issue title: E-MRS Fall Meeting 2005

Article type: Research Article

Authors: Yang, Zhiqing^{a; *} | Schryvers, Dominique^a

Affiliations: [a] Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

Correspondence: [*] Corresponding author. E-mail: zhiqing.yang@ua.ac.be

Abstract: Composition gradients surrounding Ni_4Ti_3 precipitates in a Ni_{51}Ti_{49} B2 austenite matrix are investigated by a combination of analytical TEM techniques, including electron energy loss spectroscopy (EELS), energy filtered TEM (EFTEM) and energy dispersive X-ray spectroscopy (EDX). A Ni depleted zone in the surrounding matrix was detected. The size and concentration change of the depletion zone compensate very well for the excess Ni in the precipitate. Since different precipitates are often formed in nanoscale proximity, depletion zones from different precipitates can enforce one another in certain regions. A new quantification technique of EELS confirmed the 4:3 atomic ratio between Ni and Ti for the precipitate. No Ni-rich zone in the vicinity of grain boundaries was detected in the solution-treated samples.

Keywords: NiTi, precipitate, EELS, EFTEM, EDX

DOI: 10.3233/JAE-2006-711

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 23, no. 1-2, pp. 17-24, 2006