Effect of Mo addition on microstructure and vacuum arc characteristics of CuCr50 alloy

The work functions of Cu, Cr, Mo and CrMo were calculated utilizing the first principle. The effect of Mo addition on the microstructure of CuCr50 alloy was characterized by a scanning electron microscope, and the arc motion characteristic was recorded and investigated by a digital high-speed video camera. The calculated results show that the selectivity of breakdown is closely related to the work function of close-packed plane. The experimental results show that Mo addition can strengthen Cr phase, the first breakdown transfers from Cr phase to Cu phase, and the cathode spots present the characteristics of division and deviation, thus avoiding concentrated erosion. In addition, the chopping current is reduced and the breakdown strength is enhanced as well.

► The selectivity of breakdown is closely related to the work function of close-packed plane.
► The Mo addition can transfer the first breakdown from Cr phase to Cu phase of CuCr50 alloy.
► The cathode spots of CuCr alloy with Mo addition show the characteristics of division and deviation.