In situ studies of the martensitic transformation in epitaxial Ni-Mn-Ga films

被引：60
作者：
Buschbeck, J. [1 ,2 ]
Niemann, R. [1 ]
Heczko, O. [1 ,3 ]
Thomas, M. [1 ]
Schultz, L. [1 ,2 ]
Faehler, S. [1 ]
机构：
[1] IFW Dresden, D-01171 Dresden, Germany
[2] Tech Univ Dresden, Inst Mat Sci, Dept Mech Engn, D-01062 Dresden, Germany
[3] Acad Sci Czech Republic, Inst Phys, Prague 18202, Czech Republic
来源：
ACTA MATERIALIA | 2009年 / 57卷 / 08期
关键词：
Magnetic shape memory alloy; Martensitic phase transformation; Thin films; Interfaces; Twinning; NI2MNGA SINGLE-CRYSTALS; FIELD-INDUCED STRAIN; MAGNETIC-ANISOTROPY; ALLOYS; PHASE; DEPENDENCE;
D O I：
10.1016/j.actamat.2009.02.008
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The martensitic transformation of epitaxial Ni-Mn-Ga films is investigated with respect to changes of structure, microstructure, magnetic and electronic properties. For this, temperature dependent atomic force mciroscopy (AFM), X-ray, magnetization and resistivity measurements are performed in situ, during martensitic transformation of a 500 nm thick film. The combination of these methods gives a comprehensive understanding of the martensitic transformation and allows to identify differences of constrained epitaxial films compared to bulk. Experiments show the formation of a twinned, orthorhombic martensite with high uniaxial magnetocrystalline anisotropy from the austenite around room temperature. High resolution AFM micrographs directly reveal how martensite variants grow and show the converging of variants nucleated at different nucleation sites. While most features are in agreement with a first-order transformation, the transformation proceeds continuously to lower temperatures, an effect which can be explained by the constraint from the substrate. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码：2516 / 2526
页数：11
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