Effects of process parameters on the surface quality, microstructure and mechanical properties of Cu-12%Al wires fabricated by continuous unidirectional solidification

Cu-12%Al alloy wires with a diameter of 6 mm were prepared by vacuum melting and argon shield vertical continuous unidirectional solidification process. The effects of melt temperature, crystallizer length and drawing velocity on the surface quality, microstructure and mechanical properties of the alloy wires were investigated. The results show that single-crystalline or columnar-crystalline wires can be fabricated at a crystallizer length of 20 to 40 mm, a melt temperature of 1100 to 1250℃ and a drawing velocity of 10 to 70 mm·min^-1. Shortening the crystallizer length, raising the melt temperature and/or increasing the drawing velocity are in favor of improvements in the surface quality, but the continuous columnar-crystalline wires can be obtained at a lower melt temperature, a longer crystallizer length and/or a higher drawing velocity. With the increase of drawing velocity, the cross-sectional grain size of the wires decreases firstly and then increases in the parameter regions of the crystallizer length of 30 mm, the melt temperature of 1 100 to 1 150℃ and the drawing velocity of 10 to 70 mm·min^-1. The continuous columnar-crystalline wires manufactured at the crystallizer length of 30 mm, the melt temperature of 1 150℃ and the drawing velocity of 30 mm·min^-1 have a good elongation percentage of 25.7%.