Effect of boron on the microstructure and properties of Cu–15Ni–8Sn alloy

Cu–15Ni–8Sn alloy stands out as a superior alternative to toxic and expensive Cu–Be alloys, due to its high strength and excellent corrosion resistance, particularly in applications such as deep-sea pipelines, bearings, and electronics in marine engineering. In this work, effect of boron on the mechanical properties and corrosion behavior of Cu–15Ni–8Sn alloy has been investigated. It was indicated that the precipitation of the second phase Ni 6.67 SnB 2 can significantly inhibit the formation and growth of discontinuous precipitates. The higher content of elemental boron, the greater the number of the second phase under the condition of controlling the amount of boron added in this experiment. This leads to a subsequent rise in hardness, with the highest recorded hardness reaching 368 HV. The alloy also exhibits commendable tensile strength, with the ultimate tensile strength, elongation, and yield strength enhanced to 1.08 GPa, 14.3 %, and 862.7 MPa, respectively. Furthermore, the corrosion resistance of the Cu–15Ni–8Sn alloy was demonstrated to improve by electrochemical corrosion test after the introduction of boron. • The addition of boron can significantly inhibit the formation and growth of discontinuous precipitates in Cu–15Ni–8Sn alloys, and reduces the segregation of Sn at grain boundaries. • A certain amount of boron can improve the corrosion resistance of Cu–15Ni–8Sn alloys. • The ultimate tensile strength, elongation, and yield strength of Cu–15Ni–8Sn-0.10B alloy improved to 1.08 GPa, 14.3 %, and 862.7 MPa, respectively.