Effect of Minor Additions of Misch Metal on the Electrical and Mechanical Properties of Silver

Abstract

AbstractThe effect of rare earth misch metal in concentrations of 0.01–0.2 wt% on the mechanical properties and electrical resistivity of pure silver is investigated. It is found that the misch metal additions up to 0.05 wt% increased (∼38%) the hardness of silver without significantly (less than 8%) altering the electrical resistivity of silver. However, with increasing misch metal contents from 0.05 to 0.2 wt%, the hardness increase was observed to be less than 16% whilst electrical resistivity increased by 75%. The misch metal additions as low as 0.05 wt% to silver have also been found to increase the erosion resistance of electrical contacts significantly. The hardening effect of rare earths seems primarily due to refinement of structure as a result of formation of rare oxides dispersed particles which exert restraining influence on the movement of boundary. The fine dispersed precipitates in the silver matrix seem also to impart non-welding properties which prevent the hot surfaces of contacts from s...