Outstanding mechanical and magnetocaloric properties of MnCoGe alloy fabricated through hot pressing sintering

Abstract

MnCoGe-based alloys represent promising candidates for magnetic refrigeration due to their advantageous Curie temperature and structural transition temperature near room temperature, coupled with exceptional magnetocaloric effect (MCE). However, the practical application of these materials is constrained by their inferior mechanical properties. Although resin bonding enhanced these properties, it simultaneously detracted from the MCE. In order to overcome this challenge, a novel synthesis method combining arc melting and hot press sintering is proposed. This approach led to an enhancement in the mechanical properties of MnCoGe-based alloys without compromising their MCE. The results of our investigation indicated that the Mn1·16Co0.84Ge alloy has achieved an unprecedented compressive stress of 367 MPa. At room temperature, this alloy undergoes a first-order martensitic phase transformation characterized by a mixed crystal structure comprised of hexagonal austenite and orthorhombic martensite. Furthermore, the Mn0·91Co1.09Ge alloy demonstrated a maximum isothermal entropy change of 19.5 J/kg K under a 7 T magnetic field. This study establishes a robust framework for designing high-performance magnetic refrigeration materials that integrate excellent mechanical properties with superior MCE.

Keywords

• MnCoGe alloy
• Mechanical properties
• Crystal structure
• Magnetocaloric effect