Phase transformation and magnetic properties in Ni–Mn–Ga Heusler alloys

Ingale, Babita; Raja, M. Manivel; Gopalan, R.; Chandrasekaran, V.; Ram, Sanjay K.

doi:10.1016/j.jallcom.2006.06.003

Cited by 39 publications

(18 citation statements)

References 21 publications

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“…1a). Compared with 2 2 0 diffraction peak, which is the strongest one of the 2:17R phase, the 0 0 6 diffraction peak along the easy magnetization direction of the 2:17R is relatively low, which indicates there is no evident [21] preferred orientation growth in the as-cast master alloy during cooling. The ribbons prepared by as-cast master alloy, which are melt-spun at 20 m/s, mainly consist of TbCu 7 -type Sm(Co, M) 7 (M = Fe, Cu, Zr) phase (for short 1:7H) (see Fig.…”

Section: Phase Analysismentioning

confidence: 95%

Sm12Co59Cu6Fe20Zr3 sintered magnets made from as-cast alloy and melt-spun ribbons

Sun

Zhang

Cui

et al. 2009

Journal of Alloys and Compounds

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Section: Phase Analysismentioning

confidence: 95%

Sm12Co59Cu6Fe20Zr3 sintered magnets made from as-cast alloy and melt-spun ribbons

Sun

Zhang

Cui

et al. 2009

Journal of Alloys and Compounds

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“…5,7,13,23,24 However it is not so often in bulk polycrystalline FSMAs where the low-field magnetization generally keeps unchanged between T A and T C . [25][26][27][28] Up until now there is no report on the thermomagnetization behavior of the FSMA ribbons annealed at high temperature over 1000 K. Here after annealing at 1073 K the austenite magnetiza- tion M aust ͑100 Oe͒ between T A and T C varies in a way that FSMAs behave under high magnetic field ͑generally over 1 T͒ ͑Refs. 25, 26, 29, and 30͒ or that the saturation magnetization M S ͑T͒ / M S ͑0͒ typically acts as a function of the temperature T / T C for ferromagnetic materials.…”

Section: B Magnetic Characteristicsmentioning

confidence: 99%

Anomalous magnetizations in melt spinning Ni–Mn–Ga

Wang

Jiang

Techapiesancharoenkij

et al. 2009

Journal of Applied Physics

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The structural and magnetic characteristics were studied for martensitic and austenitic Ni-Mn-Ga melt-spun ribbons of as quenched and as annealed at different temperatures. No essential structure change was found before and after annealing, but there are some anomalies in the magnetization process. In the austenite state the M͑T͒ curves measured in 100 Oe field exhibit a Hopkinson peak at T C for the ribbons of as quenched and annealed at 573 and 773 K, but the curves monotonically decays to zero with the increasing temperature to T C after annealing at 1073 K. In the martensite phase of both as quenched and 573 K annealed ribbons an abrupt increase in the slope of the M͑H͒ curve was observed; it appears to be due to the onset of magnetic-field-induced twin boundary motion. The abrupt slope change disappeared in the ribbons annealed at temperatures higher than 773 K. The ribbon processing history and particularly the quenched-in internal stress were modeled to probe the possible mechanisms for the anomalous magnetization behaviors, combining the grain-grain strain stored in the polycrystalline. The annealing temperatures were clarified into three groups according to their effects on the magnetization behaviors of the austenite and martensite.

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“…They concluded that this alloy, on heating, undergoes a first-order magnetocrystalline transition from tetragonal martensite to a cubic austenite structure at a transformation temperature, T M , ranging from 175 K to 220 K; followed by a second-order ferromagnetic-paramagnetic transition identified with a Curie temperature of the austenite phase, T C , between 375 K and 380 K; the transitions are reversible with temperature [10,11]. Later it was found [12][13][14][15][16] that the supposed transition temperatures, T M and T C , could made nearly coincident either by doping the alloy with Co or Cu or by slightly varying the alloy composition in the off-stoichiometric form of Ni 50+X Mn 25−X−Y Ga 25+Y , with X ≈ 5 and Y ≈ l-2. The isothermal magnetization versus field loops displayed large hysteresis losses and the magnetization characteristics indicative of a field-induced magneto-structural phase transformation [17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%