Microstructure of Contact Material Modified by High-Current Vacuum Arc

The paper presents research results into the microstructure of Cu–Cr composite material affected by the highcurrent vacuum arc. The investigation of the electrode cross-sections allows us to emphasize two zones both for anode and cathode: 1) the exposure zone of the vacuum arc and 2) the virgin material. The first zone locates on the surface of electrodes and is just a zone that crystallizes after the electrode melting due to the exposure to the high-current vacuum arc. It is interesting that on anode there appears a narrow, transition layer enriched with chromium nearby the virgin material and with copper in the exposure zone of the vacuum arc. The formation of such a layer on cathode is not observed.