Microstructure, Wear and Corrosion Performance of Cold Metal Transfer Additive Manufactured (Ni, Ti)-Modified Nickel Aluminum Bronze Alloy

Nickel aluminum bronze alloy is designed and fabricated by cold metal transfer additive manufacturing (CMTAM) through feeding ERCuNiAl wires with the addition of trace nickel and titanium powders, aiming at improving the wear and corrosion performance. Experimental results show that the alpha-Cu + gamma 2(Cu9Al4) + kappa(Fe,Ni)Al phases formed for the sample without nickel and titanium addition and 0.3 wt% (Ni,Ti)-modified nickel aluminum bronze. Additionally, the alpha-Cu + kappa(Fe,Ni)Al + (Ni,Fe)2AlTi phases are observed for 0.6 and 0.9 wt% (Ni,Ti)-modified nickel aluminum bronze. The (Ni,Fe)2AlTi phases are in situ synthesized with the addition of nickel and titanium content, thus forming the heterogeneous nucleation sites and suppressing the formation of corrodible gamma 2 phase. The grain is refined significantly. The specific wear rate of (Ni,Ti)-modified nickel aluminum bronze decreased by up to 34.0%, which is 0.68 mm3/N m when the addition of nickel and titanium content is increased to 0.6 wt%. The corrosion current density of the samples exhibits a downtrend from 5.50 x 10-6 to 2.33 x 10-6 A/cm2. The improvement of corrosion resistance of (Ni, Ti)-modified nickel aluminum bronze is mainly attributed to the gradual formation of stable and dense passive film and the gradual reduction corrodible gamma 2 phase.