Electronic beam surface remelting of Cu-Cr contact materials

Cu-Cr alloys have been widely used as an electrical contact material for medium-voltage and high-power vacuum interrupters. The performance of the Cu-Cr contact material depends strongly on chemical composition, grain size of high-melting Cr-rich solid solution, and defects. Few experimental studies showed that nanocrystalline Cu-Cr material possesses improved switching performance with respect to conventional coarse-grained material. Recent studies further showed that electron beam remelting can reduce the size of Cr-rich particles significantly, opening a new opportunity of improving switching performance of the conventional Cu-Cr material. In the present work, several Cu-Cr alloy samples with different Cr content were processed using the electron beam remelting technique. The microstructure of the remelted surface layer of the alloy samples was investigated. The results are discussed by reference to a newly established Cu-Cr phase diagram.