Structure analysis of a precipitate phase in an Ni-rich high-temperature NiTiHf shape memory alloy

被引：147

作者：

Yang, F. ^{[1
]}

Coughlin, D. R. ^{[1
]}

Phillips, P. J. ^{[2
]}

Yang, L. ^{[1
]}

Devaraj, A. ^{[3
]}

Kovarik, L. ^{[3
]}

Noebe, R. D. ^{[4
]}

Mills, M. J. ^{[1
]}

机构：

[1] Ohio State Univ, Columbus, OH 43210 USA

[2] Univ Illinois, Chicago, IL 60608 USA

[3] Pacific NW Natl Lab, Richland, WA 99354 USA

[4] NASA Glenn Res Ctr, Cleveland, OH 44135 USA

来源：

ACTA MATERIALIA | 2013年 / 61卷 / 09期

关键词：

Shape memory alloys (SMAs); Precipitation; Crystal structure; High-angle annular dark field (HAADF); Ab initio electron theory; TOTAL-ENERGY CALCULATIONS; MARTENSITIC-TRANSFORMATION; ULTRASOFT PSEUDOPOTENTIALS; MICROSTRUCTURE; TRANSITION; SIMULATION;

D O I：

10.1016/j.actamat.2013.02.023

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Thermal aging of the high-temperature shape memory alloy 50.3Ni-29.7Ti-20Hf (at.%) introduces a novel precipitate phase that plays an important role in improving shape memory properties. The precipitate phase was investigated by conventional electron diffraction, high-resolution scanning transmission electron microscopy (STEM) and three-dimensional atom probe tomography. An unrelaxed orthorhombic atomic structural model is proposed based on these observations. This model was subsequently relaxed by ab initio calculations. As a result of the relaxation, atom shuffle displacements occur, which in turn yields improved agreement with the STEM images. The relaxed structure, which is termed the "H phase", has also been verified to be thermodynamically stable at 0 K. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：3335 / 3346

页数：12

共 25 条

[1] Load-biased shape-memory and superelastic properties of a precipitation strengthened high-temperature Ni50.3Ti29.7Hf20 alloy [J].