Structure of Ni49Mn29Ga21 shape memory alloy processed by Bridgman method

Rafał Wróblewski 1Marcin Leonowicz 1Marek Szczerba 2

1. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
2. AGH University of Science and Technology, Faculty of Non-Ferrous Metals, Al. Mickiewicza 30, Kraków 30-059, Poland

Abstract

Ferromagnetic shape memory alloys (FSMA) are capable of producing, magnetically induced strain of several percent at frequencies of the order of 1 kHz. The best performance exhibit alloys based on the Ni-Mn-Ga system. Off-stoichiometric single crystals of Ni2MnGa phase can produce up to 10% strain in the field below 1T.
In this study the Ni49Mn29Ga21 alloy was prepared by arc melting of the pure elements followed by the modified Bridgman growth method. Structure and phase transition temperatures were studied. The X-ray diffraction patterns as well as magnetic measurements and SEM observations revealed a presence of martensite at room temperature. The magnetization vs. temperature curve showed the martensite-to-austenite transformation starting at 290K and the Curie temperature at 390K.
The effect of thermal treatment on the structure was investigated.

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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium E, by Rafał Wróblewski
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-14 16:17
Revised:   2009-06-07 00:44
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