Constitutive modeling of Ni–Mn–Ga ferromagnetic shape memory alloys under biaxial compression

Abstract

Ferromagnetic shape memory alloys are a type of shape memory alloys that exhibit inelastic strains when subjected to magnetic fields. So far, several constitutive models have been proposed to predict ferromagnetic shape memory alloys' behaviors under the application of a magnetic field and a compressive stress. In this article, an available constitutive model in a continuum framework is used to investigate the behaviors of Ni-Mn-Ga under biaxial compressive stresses. Since the required model parameters in the original approach are not unique for all loading conditions, the model is modified so that a unique set of model parameters suffices to study different loading conditions. Loading history is also considered in an improved way, and two-dimensional phase diagram is generalized to three-dimensional phase diagram, called reorientation surface in this work, to directly enter the effects of loading history on reorientation start conditions. The orthogonality property of a surface and its gradient vector are used to obtain the general conditions which must be satisfied to ensure continuation of reorientations.

Magnetocaloric materials: From micro- to nanoscale

“…Ferromagnetic shape memory alloys (FSMAs) or magnetic shape memory alloys (MSMAs) are terms technically attributed to the materials that have the ability to show deformations when subjected to magnetic fields and that present two (typically, austenite and martensite) or more crystallographic phases for which reversible transitions from one to the other occur through diffusion-less transformations. 106 The MSMAs were discovered in 1996 when the Ni 2 MnGa 107 was first studied. A few years later, Hu et al 10 unveiled that Ni 51.5 Mn 22.7 Ga 25.8 displays a large MCE due to the martensitic to austenitic structural transition.…”

بررسی تأثیر تنش جانبی بایاس‌کننده بر رفتار مکانیکی - مغناطیسی تک کریستال آلیاژ حافظه‌دار مغناطیسی

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