Interplay between temperature and composition effects on the martensitic transformation in Ni(2+x)Mn(1-x)Ga alloys
2011 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 26, 261903- p.Article in journal (Refereed) Published
Martensitic transformation in Ni(2+x)Mn(1-x)Ga alloys is known to be controlled by the soft tetragonal elastic constant C' of the high-temperature austenitic phase. The temperature (T) and composition (x) dependence of C'(T, x) are calculated using the first-principles exact muffin-tin orbitals method. We show that the temperature factor of C' is dominated by the phonon-smearing term. The competition between the negative alloying effect (partial derivative C'/partial derivative x < 0) and the positive temperature effect (partial derivative C'/partial derivative T > 0) is found to lead to nearly constant C'(T(M)(x), x) at the critical temperature TM(x). We demonstrate that a proper account of the temperature and composition dependence of C'(T, x) is indispensable for reasonable theoretical TM(x) values.
Place, publisher, year, edition, pages
2011. Vol. 98, no 26, 261903- p.
IdentifiersURN: urn:nbn:se:kth:diva-37167DOI: 10.1063/1.3603935ISI: 000292335700013ScopusID: 2-s2.0-79960090172OAI: oai:DiVA.org:kth-37167DiVA: diva2:432315