Unveiling the enhancement of mechanical properties in cryogenic-treated Sm2Co17 permanent magnets without sacrifice of magnetic properties

Abstract

SmCo permanent magnets are used in some of the strongest permanent magnets, particularly for applications between about 200 and 550 °C. However, their brittleness limits their practical use. Improving their mechanical properties is therefore of great practical significance. Cryogenic treatment is firstly applied in SmCo permanent magnets to enhance the mechanical properties. The flexural strength has been increased by 14.3% along the weakest orientation, and the impact toughness has been increased by 7.0%. After cryogenic treatment, the intrinsic coercivity is slightly increased, and the other magnetic properties are almost unchanged, which is different from other methods to improve mechanical properties at the expense of magnetic properties. The enhancement of flexural strength and impact toughness primarily stems from a decrease in residual stress. This study provides an effective and convenient approach to enhance the mechanical properties in Sm2Co17 permanent magnets without sacrifice of magnetic properties.