Arc ablation behavior and microstructure evolution of plastically deformed and micro-alloyed Cu-Cr-Zr alloys

Cu-Cr-Zr alloys are often subjected to premature failures due to arc erosion at moment of their breakdown. In this paper, a series of simulated high-voltage arc ablation experiments were conducted to systematically investigate arc ablation characteristics of Cu-Cr-Zr alloys, their microstructure evolutions and anti-ablation properties after plastic deformation and microalloying. Results showed that during their arc ablation processes, a halo pattern was firstly formed on the surface under the action of high-temperature arc. This is followed by partial melting and splashing of Cu, forming of uneven and rough surfaces, and finally significant burning of the alloy. The degree of ablation of alloy is aggravated with the increased breakdown voltage. Due to a combined effect of solid solution strengthening, fine grain strengthening and deformation strengthening, the ablation resistance of the micro-alloyed and plastically deformed alloy has been significantly improved. The breakdown field strengths of commercial Cu -Cr-Zr alloy, heat-treated and deformed one, micro-alloyed and heat-treated one are 1.46 x 10(6) V/m, 1.67 x 10(6) V/m and 1.90 x 10(6) V/m, respectively. However, the breakdown strength of alloys after microalloying is unstable. Results show that there are no preferred phases for the first breakdown of arc ablation of Cu-Cr-Zr alloys. The second-phase particles with high-hardness and high-melting temperature hinder the splashing and flow of the molten copper, and inhibit the movement of the cathode spots during the ablation process. (C) 2019 Elsevier B.V. All rights reserved.