Correlation between composition and phase transformation temperatures in Ni-Mn-Ga-Co ferromagnetic shape memory alloys

被引：43
作者：
Sanchez-Alarcos, V. [1 ]
Perez-Landazabal, J. I. [1 ]
Recarte, V. [1 ]
Gomez-Polo, C. [1 ]
Rodriguez-Velamazan, J. A. [2 ,3 ]
机构：
[1] Univ Publ Navarra, Dept Fis, Navarra 31006, Spain
[2] Univ Zaragoza, CSIC, Inst Ciencia Mat Aragon, Zaragoza, Spain
[3] Inst Max Von Laue Paul Langevin, CRGs D1B D15, F-38042 Grenoble, France
来源：
ACTA MATERIALIA | 2008年 / 56卷 / 19期
关键词：
Ni-Mn-Ga-Co; Ferromagnetic shape memory alloys; Martensitic transformation; Curie temperature; Crystal structure;
D O I：
10.1016/j.actamat.2008.07.017
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The effect of Co addition on the phase transformation temperatures (martensitic and Curie point) and crystal structure of Ni-Mn-Ga-Co shape memory alloys has been investigated on (Ni50.26Mn27.30Ga22.44)(100-x)Co-x (x = 0, 2, 4, 6) alloys as well as on alloys having different Ni/Mn/Ga ratios and a fixed amount of Co. Alloying by Co affects the martensitic transformation temperature and the transformation enthalpy change mainly through the change on the valence electron concentration (e/a), but the transformation entropy is almost unaffected. On the other hand, the composition (analyzed through the e/a ratio) shows a different influence on the Curie temperature depending on the crystallographic phase (austenite or martensite) in which the magnetic ordering takes place. It is also reported that in Ni-Mn-Ga-Co alloys the Curie temperature of the martensitic phase is lower than that of the austenitic phase, opposite to what occurs in tertiary Ni-Mn-Ga alloys. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码：5370 / 5376
页数：7
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