Competing tetragonal and monoclinic phases in Ni2.2Mn0.80Ga

Ranjan, Rajeev and Singh, Sanjay and Boysen, Hans and Trots, Dmytro and Banik, S and Awasthi, AM and Mukhopadhyay, PK and Barman, SR (2009) Competing tetragonal and monoclinic phases in Ni2.2Mn0.80Ga. In: Journal Of Applied Physics, 106 (3). 033510-1-033510-8.

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Abstract

Temperature dependent synchrotron x-ray powder diffraction, differential scanning calorimetry, and magnetic measurements were performed on Ni2+xMn1-xGa (x=0.20 and 0.35) magnetic shape memory alloys. For x=0.20, though the monoclinic phase is thermodynamically stable, a trace of residual stress can stabilize a tetragonal phase. The residual-stress-induced tetragonal phase transforms to the cubic austenite phase over an unusually large temperature range (348 K < T < 693 K), suggesting extremely slow kinetics of transformation. In contrast to x=0.20, the thermodynamically stable phase of x=0.35 is tetragonal and this composition exhibits the usual features of a reversible martensitic transformation. The results suggest that for x=0.20 the monoclinic and tetragonal phases are nearly degenerate.

Item Type:	Journal Article
Publication:	Journal Of Applied Physics
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	differential scanning calorimetry; ferromagnetic materials; gallium alloys; magnetic transitions; manganese alloys; nickel alloys; reverse martensitic transformations; shape memory effects; solid-state phase transformations; thermodynamics; X-ray diffraction.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	08 Sep 2009 09:33
Last Modified:	19 Sep 2010 05:44
URI:	http://eprints.iisc.ac.in/id/eprint/22948

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