Effects of Ti Addition on Microstructure, Mechanical Properties and Corrosion Resistance of the Cu-Zn-Ni Alloy

The effects of Ti addition on the microstructure, mechanical properties and corrosion resistance of the Cu-30Zn-6Ni-1.5Ti (wt.%) alloy were investigated in the present study. Microstructure analysis confirms that the Ni3Ti and NiTi phases are formed in the Cu-Zn-Ni-Ti alloy. Most of the Ni3Ti particles dissolve into the matrix, whereas NiTi particles remained after the solution treatment. Moreover, nano-sized Ni3Ti and Cu2NiZn phases are precipitated from the matrix during the aging process. The yield strength improvement of the studied alloy is attributed to the Orowan strengthening (accounting for 42.5% of the total yield strength), then the grain boundary strengthening (31.1%), the dislocation strengthening (16.9%), the twin boundary strengthening (5.0%) and the solid solution strengthening (0.5%). After cold rolling with 90% deformation and aging at 440 °C for 1 h, the designed alloy has a hardness of 327.1 HV, a yield strength of 1192 MPa, an ultimate tensile strength of 1297 MPa, an elongation of 1.8%, an electrical conductivity of 11.2% IACS and a corrosion rate of 2.8 μm/month in 3.5% NaCl solution.