Open AccessThe thermal and magnetic pre-treatments dependence of the magneto-mechanical behavior of Ni-Mn-Ga single crystal
Author(s) -
Lü Zhao-Cheng,
Guang Li
Publication year - 2009
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.58.2746
Subject(s) - materials science , condensed matter physics , magnetism , curie temperature , diffusionless transformation , austenite , ferromagnetism , magnetization , paramagnetism , martensite , magnetic field , single crystal , magnetic domain , magnetic shape memory alloy , magnetic refrigeration , nuclear magnetic resonance , metallurgy , microstructure , physics , quantum mechanics
The effects of thermomagnetic pretreatments on the magnetism and mechanical properties of Ni50.3Mn28.7Ga21 single crystal were studied. Two samples A and B were heated to a temperature above their Curie temperature TC and then cooled down to room temperature via different cooling processes. An external magnetic field was applied during cooling of sample A from T>TC to room temperature. For sample B, the same magnetic field was applied at T below its TC but higher than its austenite to martensitic transformation temperature during cooling. The reversible strain and change in magnetization ΔM measured at room temperature for sample A are much smaller than those for sample B. It was supposed that with the appearance of the magnetic field during the transformation from austenite to martensitic phase, the field tends to induce a favorable single martensitic domain in sample B, leading to the greater reversible strain and ΔM. However, preferential magnetic domains may develop in sample A by applying the same magnetic field during the transition from paramagnetism to ferromagnetism, leading to the different alignments of martensitic domains from those in sample B. This might be the reason for the smaller reversible strain and ΔM in sample A.