Temperature dependence of magnetically induced deformation of Ni–Mn–Ga martensite

Victor Lvov 1Nadiya Glavatska 2Illya Glavatskyy 2

1. National Taras Shevchenko Kiev University, Department of Radiophysic (KNU), 64, Volodymyrska str., Kyiv, Ukraine
2. Institute for Metal Physics, N.A.S.U., 36 Vernadsky Boulevard, Kyiv 03142, Ukraine

Abstract

In the present work all known factors contributing to the temperature dependence of the magnetic field induced strain (MFIS) in Ni–Mn–Ga martensite are considered in the framework of statistical model elaborated in [1,2]. These factors are the temperature dependencies of: (i) crystal lattice parameters [3], (ii) Young modulus [4], (iii) saturation magnetization and (iv) thermal fluctuations of the microstress. Both individual and cooperative effects of these factors on MFIS are studied. The effect of the factors (i) – (iv) on the achievable MFIS value and on the characteristic values of magnetic fields, which "switch on" and saturate MFIS, is estimated. It is shown, that all factors affect both the achievable MFIS value and characteristic fields under the real experimental conditions, none of them can be neglected during the quantitative theoretical analysis of the experimental strain–field dependencies obtained for the different temperature values. In addition, the influence of specimen’s shape on the characteristic fields is illustrated for different temperature values. For the available experimental dependencies (i) – (iii) and the reasonable set of model parameters the switching magnetic field proved to be equal to 160 kA/m when the temperature was 15 K below the martensite start temperature and to 320 kA/m when the temperature was 45 K below the martensite start temperature. Obtained results agree with the experimental data reported in [5]. References: [1] V.A. L’vov, O. Rudenko, N. Glavatska. Phys. Rev., B 71 (2005) 024421-6. [2] V.A. L’vov, N. Glavatska, I. Glavatskiy, Y. Ge, O. Heczko, O. Söderberg, S.-P. Hannula. Int. J. Appl. Electromagn. Mech., 23 (2006) 75-79. [3] N. Glavatska, I. Glavatskiy, G. Mogylny, S. Danilkin, D. Hohlwein, O. Söderberg, V. Lindroos and A. Beskrovnij. J. Phys. IV, 112 (2003) 963-967. [4] V. A. Chernenko, J. Pons, C. Seguí, E. Cesari. Acta Mater., 50 (2002) 53-60. [5] O. Heczko, L. Straka. J. Appl. Phys, 94 (2003) 7139.

 

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Presentation: Oral at E-MRS Fall Meeting 2007, Symposium E, by Victor Lvov
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-10 15:22
Revised:   2009-06-07 00:44