Microstructure, mechanical properties and corrosion resistance properties of Ni-Co- Mn-Sn-Gd magnetic shape memory alloys

Abstract

Ni-Mn-Sn alloy is considered to be one of the most potential refrigerant, sensor and driver materials, but its practical application is hindered to a large extent due to the inherent brittleness of intermetallic compounds.The microstructure, martensitic transformation, mechanical properties and seawater corrosion resistance of Ni45Co5Mn38Sn12-xGdx(x=0.3, 0.6, 1, 1.5, atom fraction/%, the same below) magnetic shape memory alloy were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron universal capacity testing machine and electrochemical workstation.The experimental results show that when the content of Gd is 0.3%, a mottled precipitate phase appears, and a particle precipitate phase is found around the mottled precipitate phase. The two precipitates increase gradually and are connected together in a network distribution. The doping of Gd increases the concentration of valence electrons in the alloy matrix, which leads to the increase of the alloy martensitic transformation temperature. When Gd content is 1.5%, the compressive strength of the alloy can reach 1258 MPa and the compressive fracture strain can reach 13.7%. In addition, the corrosion resistance of Ni-Co-Mn-Sn-Gd alloy is better than that of 304 stainless steel, and the corrosion resistance of the alloy gradually increases with the increase of Gd content.

Keywords

• mechanical property
• microstructure
• martensitic transformation
• corrosion resistance property
• ni-co-mn-sn-gd magnetic shape memory alloy