Abstract
A phase-field model was developed to simulate the ferromagnetic domain structure and martensite variant microstructure of Ni-Mn-Ga shape-memory alloy. The evolution of reversible magnetic-field-induced strain (MFIS) and associated magnetic domain/martensite variant structure were modeled under an external magnetic field. It was found that MFIS increased significantly from 0.2% to 0.28% as the temperature increased from 265 K to 285 K. In addition, compressive pre-stress efficiently enhanced the MFIS of the alloy, while tensile stress reduced MFIS. Furthermore, it was proved that there was possibility of achieving similar enhancement of MFIS by replacing compressive stress with perpendicular biaxial tensile stress. The results revealed that the residual variant induced by stress plays an important role in the reversible MFIS effect.
Highlights
State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Abstract: A phase-field model was developed to simulate the ferromagnetic domain structure and martensite variant microstructure of Ni-Mn-Ga shape-memory alloy
magnetic-field-induced strain (MFIS) was observed in the simulation, which can be attributed to the residual variant boundary movement led by defects of the samples
The results showed that MFIS increased significantly from 0.2% to 0.28% as the temperature increased from 265 K to 285 K
Summary
State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Abstract: A phase-field model was developed to simulate the ferromagnetic domain structure and martensite variant microstructure of Ni-Mn-Ga shape-memory alloy. The evolution of reversible magnetic-field-induced strain (MFIS) and associated magnetic domain/martensite variant structure were modeled under an external magnetic field. It was proved that there was possibility of achieving similar enhancement of MFIS by replacing compressive stress with perpendicular biaxial tensile stress. Since the large magnetic-field-induced strain (MFIS) was discovered, this intermetallic material has been a potential candidate for a wide variety of possible applications, such as actuators, sensors, etc. In order to achieve the properties similar to a single-crystal material, the grain texture should be processed to make more grain orientations towards the same direction. The other issue is that the irrecoverable MFIS of Ni-Mn-Ga alloy makes it difficult in applications. To address this problem, Hua et al [18] developed. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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