Microstructure and Mechanical Properties of Cu–12Al–xNi Alloy Prepared Using Powder Metallurgy

The study investigated the effect of nickel content on the microstructure and mechanical properties of Cu-12Al-xNi alloys prepared using powder metallurgy. The results indicated that the alloys investigated consisted of alpha-Cu and gamma(2) (Al4Cu9), containing less than 4 wt% Ni content. The alpha-Cu phase gradually increased, while the gamma(2) (Al4Cu9) phase gradually decreased as the sintering temperature increased. Both the strength and hardness of the alloy thus reduced. When the Ni content increased above 4 wt%, the NiAl phase precipitated at the grain boundaries, which resulted in an increase in the strength of the alloy. Additionally, the tensile strength reached a maximum of 390 MPa when the Ni content reached 6 wt%. The decrease in the tensile strength for higher Ni content was attributed to the formation of a NiAl phase network. And the addition of nickel did not significantly alter the sintering density of the alloy. The mechanisms of microstructure evolution and strengthening mechanisms were investigated and discussed.