Effect of Process Parameters on the Interface Microstructure and Thickness of Silver Cladding Copper Wires Prepared by Core-Cladding Continuous Casting

Abstract

Liquid silver and solid copper with diameter of 8 mm were used as raw materials, and the silver cladding copper (SCC) wires with a diameter of 10 mm were prepared by the self-developed core-cladding continues casting (CCC) method at the silver casting temperature of 1000–1100 °C, casting speed of 30 –90 mm min−1, cooling water temperature of 20 °C and cooling water flow of 300 L h−1. The microstructure and morphology, distribution of chemical components, and phase composition of the interface between Ag and Cu were characterized by optical microscope (OM), field emission scanning electron microscope (FESEM), and energy dispersive spectrometer (EDS). The effect of the silver casting temperature and casting speed on the interface microstructure and thickness of silver cladding copper wires and formation mechanism of the interface were investigated. The results showed that the interface microstructure which from the surface to the Cu core of the silver cladding copper wire was Ag (Cu) solid solution, hypoeutectic, eutectic and Cu (Ag) solid solution when the silver casting temperature was 1050 °C and casting speed was 30–60 mm min−1. And the interface microstructure which from the surface to the Cu core of the silver cladding copper wire was Ag (Cu) solid solution, eutectic and Cu (Ag) solid solution when the casting speed increase to 90 mm min−1 and the silver casting temperature was 1000–1050 °C. The interface microstructure which from the surface to the Cu core of the silver cladding copper wire is all hypereutectic, when the silver casting temperature was 1100 °C, casting speed was 90 mm min−1. With the increase of the casting speed, the thickness of the interface transition layer decreased sharply, the thickness of the hypoeutectic layer and Ag (Cu) solid solution layer decreased, and the eutectic layer thickness increased first and then decreased, but the thickness of Cu (Ag) solid solution remained almost constant. Under the condition of low casting temperature and high casting speed, core-cladding continues casting technology is advantageous to prepare the bimetallic composite material which is prone to eutectic reaction.