Influence of multiaxial isothermal forging on magnetocaloric effect and magnetostructural transition in Ni-Mn-Ga-Si alloy

• Published in: Journal of magnetism and magnetic materials Vol. 594; p. 171892
• Main Authors: Musabirov, I.I., Gaifullin, R.Y., Gadjiev, A.B., Aliev, A.M., Dilmieva, E.T., Krämer, S., Koshkid'ko, Yu.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.03.2024; Elsevier
• Subjects: High magnetic fields; Magnetocaloric effect; Martensitic phase; Mechanical properties; Microstructure; Phase transition; Physics; Mechanical properties; High magnetic fields; Martensitic phase; Microstructure; Magnetocaloric effect; Phase transition
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2024.171892

[Display omitted] •Influence of multiaxial forging on magnetic properties have been carried out.•After the forging the hysteresis and temperatures of martensitic transtion decrease.•Forging does not affect the sensitivity of field-induced martensitic transformation.•Inverse MCE is due to the difference in the MCA energy of austenite and martensite.•Multiaxial isothermal forging improves mechanical and functional properties. The influence of as-cast and multiaxial isothermal forged structures on the sensitivity of martensite to the magnetic field and on the magnetocaloric effect in Ni-Mn-Ga-Si alloy has been studied. In the multiaxial isothermal forged state, a “necklace” structure is observed where large grains of 100–200 µm are encompassed by a layer of fine-grained structure. In this state, the martensitic transformation occurs with a shift towards the low-temperature region of about 10 K. Characteristic points of the martensitic transformation are evaluated in a magnetic field up to 12 T, revealing a sensitivity value of 0.6 K/T for both as-cast and multiaxial isothermal forged samples. Furthermore, an inverse magnetocaloric effect is identified within the martensitic transformation region for both as-cast and multiaxial isothermal forged samples under weak magnetic fields, up to 0.2 T. This inverse effect disappears at a magnetic field of 1.8 T, leaving only the direct magnetocaloric effect observable. These findings shed light on the intriguing interplay between microstructure, magnetic sensitivity, and magnetocaloric behavior in this Ni-Mn-Ga-Si alloy, offering valuable insights for potential applications in magnetic cooling technologies.