Composition and temperature dependence of twinning stress in non-modulated martensite of Ni-Mn-Ga-Co-Cu magnetic shape memory alloys. (February 2018)

• Record Type: Journal Article
• Authors: Soroka, A.; Sozinov, A.; Lanska, N.; Rameš, M.; Straka, L.; Ullakko, K.
• Is Part Of: Scripta materialia. Number 144(2018)
• Page Start: 52
• Page End: 55
• Publication Date: 2018-02
• Subjects: Heusler phases -- Martensite -- Ferromagnetic shape memory alloy -- Magnetic shape memory -- Twinning; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2017.09.046
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: We study compositional and thermal dependences of lattice parameters and twinning stress σ TW in Ni50-x Mn25-y Ga25-z Cox Cuy + z magnetic shape memory alloys with non-modulated tetragonal crystal structure. The σ TW was found to decrease with increasing temperature with a slope from −0.0076 to −0.0181 MPa/K. The σ TW = 0.47–0.81 MPa values measured near composition-specific austenite transformation temperatures T A were discovered to depend linearly on the c / a ratio with a slope of 14 MPa. We predict that the further decrease of c / a ratio to the level of 1.085–1.104 can result in extremely low σ TW ≈ 0.1 MPa in non-modulated martensite. Graphical abstract: