Regulation of Ni-Si intermetallics in Cu-Ni-Si alloys and its influence on electrical breakdown properties

摘要

Microstructure of Cu-Ni-Si alloys, especially morphology, amount and size of Ni-Si intermetallics, was controlled by heat and thermal-mechanical treatment, and then its influence on electrical breakdown behavior was investigated systematically. Results show that first breakdown is prior to occur on the Ni_3Si phase at the grain boundary and δ-Ni_2Si in the inner of Cu matrix in Cu-Ni-Si alloys. The decrease of Ni_3Si size by using thermal-mechanical treatment can significant enhance the breakdown behavior of Cu-Ni-Si alloys since it can change the total area of preferred phase within the action area of cathode spot. As a result, the chopping current and erosion depth decrease but arc life, breakdown field and erosion area increase with the decrease of Ni_3Si size, while the precipitation δ-Ni_2Si phase has limited effect on breakdown properties. On the whole, Cu-Ni-Si alloy by solution, hot forging and aging treatments in sequence has the best breakdown properties due to the uniform dispersion of Ni_3Si phase.