Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 52: Poster II - Magnetic Heusler compounds, Magnetic shape memory alloys, Thin Films, Micro-/Nano-structured magnetic materials, Graphene, Spins in organics, Magnetic imaging, Surface Magnetism, Spin excitations/Torque, Spincaloric transport
MA 52.14: Poster
Freitag, 30. März 2012, 11:00–14:00, Poster A
A General Phase-field Model for the Martensite Rearrangement in Ni2MnGa — •Christian Mennerich1, Frank Wendler1, Marcus Jainta1, Anna Weißhaar1, and Britta Nestler1,2 — 1Karlsruhe University of Applied Sciences — 2Karlsruhe Institute of Technology
Ferromagnetic shape memory alloys have gained major interest in the last 15 years as components in actuators and dampers, as they provide large recoverable strains at low operation cost. A multi-phase field model of Allen-Cahn type has been successfully applied to describe the microstructure rearrangement in Ni2MnGa in the martensitic state, induced by external magnetic or strain fields. The model is based on a Helmholtz free energy density formulation and includes magnetic and elastic energy contributions. With order parameters that are related to the different eigenstrains of the twin variants and the spontaneous magnetization, the time-spatial evolution of the system is described by a set of partial differential equations. The evolution of the order parameters depends on energy contributions for twin interfaces and bulk phase states. To make the complex boundary value problem treatable, different techniques (staggered grids, geometric integration methods, Fast Fourier methods etc) are combined. In this contribution we describe the model, the discretization and numerical implementation. We present simulation results to show the general applicability of the model to the magnetic shape memory effect and stress induced martensite microstructure rearrangement.