A low Sn content Cu-Ni-Sn alloy with high strength and good ductility

Avoiding Sn segregation is vital to produce high performance large scale Cu-Ni-Sn alloys. In this work a low Sn-containing Cu-9Ni-2.5Sn-1.5Al-0.5Si alloy with high strength and ductility was developed by substituting Sn in Cu-Ni-Sn alloy with Al and Si. The results show that Si leads to a bimodal structure, which has coarse unrecrystallization regions with a plenty of <111> fiber texture and fine equaixed recrystallization grains. Such a bimodal structure results into good mechanical properties showing a high tensile strength of 861 MPa and a large elongation of 18%, which is comparable to Cu-15Ni-8Sn alloy. The strengthening effects are ascribed to precipitate strengthening, grain refining and twin boundary strengthening in the fine equaixed recrystallization grains and texture strengthening in the coarse unrecrystallization regions.