Effects of 1 at.% additions of Co, Fe, Cu, and Cr on the properties of Ni-Mn-Ga-based magnetic shape memory alloys. (February 2023)

• Record Type: Journal Article
• Authors: Namvari, Mahsa; Laitinen, Ville; Sozinov, Alexei; Saren, Andrey; Ullakko, Kari
• Is Part Of: Scripta materialia. Number 224(2023)
• Publication Date: 2023-02
• Subjects: Ferromagnetic shape memory -- Martensitic phase transformation -- Grain growth -- Twinning -- Ni-Mn-Ga; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2022.115116
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: The effect of Mn substitution with 1 at.% additions of Co, Fe, Cu, and Cr on the properties of a polycrystalline Ni49.8 Mn28.5 Ga21.7 magnetic shape memory (MSM) alloy after heat-treatment is examined. Doped alloys exhibit a single-phase five-layered modulated martensite structure at ambient temperature and a slight increase in martensite transformation temperatures compared to the non-doped alloy, without a substantial alteration of the Curie temperature. Cr addition decreases the grain size, while additions of Co, Fe, and Cu increase the grain size, as compared to the non-doped alloy. Particularly, Co addition leads to extreme grain growth, transforming the grain structure from polycrystalline to oligocrystalline with an average grain diameter of 2.83 mm. The Co-doped alloy demonstrates an MSM effect with a low switching field of H <0.15 T and a twinning stress of 1 MPa, which is a promising composition for use in polycrystalline-based MSM research and applications. Graphical abstract: Image, graphical abstract