Change search
ReferencesLink to record
Permanent link

Direct link
Phase stability of Ni-2(Mn1-xFex)Ga: A first-principles study
Show others and affiliations
2012 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 86, no 2, 024427- p.Article in journal (Refereed) Published
Abstract [en]

Ni-2(Mn1-xFex)Ga ferromagnetic shape memory alloy shows unusual composition-dependent martensitic transformation temperature (T-M), namely, T-M decreases with increasing e/a ratio. In hope of understanding this unusual behavior, we investigated the composition dependence of the heat of formation (H-f) and shear elastic modulus (C') of the cubic austenite as well as the stability of the five-layer modulated (5M) tetragonal martensite relative to the austenite, using first-principles exact muffin-tin orbital method in combination with coherent potential approximation. Our calculations demonstrated that H-f of the austenite increases with the Fe content x. C' increases slightly with x up to 0.05 but decreases thereafter. The composition dependence of both H-f and C' cannot fully account for the trend of T-M against x although such correlations have been proposed in literature for other Ni-Mn-Ga based alloys. The structure of 5M martensite phase of Ni-2(Mn1-xFex)Ga with 0 < x < 0.2 is determined by optimizing both the shear (changing c/a) and wavelike shuffle of atoms in (110) planes along [1 (1) over bar0] direction adopting the experimentally determined modulation function. The energy difference Delta E-AM between the austenite and 5M phases decreases with increasing x up to 0.05, following the lower Delta E-AM corresponding to lower T-M rule. However, with x larger than 0.05, Delta E-AM increases, against the experimental T-M similar to x behavior. We propose that, if taking the temperature effect and the spin-orbital coupling into account, the Delta E-AM similar to x curve might be altered and may explain the unusual composition dependence of Ni-2(Mn1-xFex)Ga.

Place, publisher, year, edition, pages
2012. Vol. 86, no 2, 024427- p.
Keyword [en]
Ni-Mn-Ga, Shape-Memory Alloys, Field-Induced Strain, Magnetic-Properties, Martensitic-Transformation, Crystal-Structures, Heusler Alloys, Potential Model, Ni2mnga, Approximation
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-101126DOI: 10.1103/PhysRevB.86.024427ISI: 000306648200005ScopusID: 2-s2.0-84864422521OAI: diva2:546742
Swedish Research CouncilEU, European Research Council, 228074

QC 20120824

Available from: 2012-08-24 Created: 2012-08-23 Last updated: 2012-08-24Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Johansson, BörjeVitos, Levente
By organisation
Applied Material Physics
In the same journal
Physical Review B. Condensed Matter and Materials Physics
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 19 hits
ReferencesLink to record
Permanent link

Direct link