Effect of Iron Addition on Microstructure and Properties of Cu-10Al-4Ni Powder Metallurgy Alloy

With copper powder, aluminum powder, nickel powder and copper-coated iron powder as raw materials, Cu-10Al-4Ni alloys containing different mass fractions (0, 1.6%, 3.2%, 4.8%, 6.4%) of iron were prepared by powder metallurgy process. The effect of iron content on the microstructure and properties of the alloy was studied. The results show that the microstructure of the alloy without iron addition consisted of Κ_Ⅲ phase, α phase and Al₄Cu₉ phase. When the mass fraction of iron was 1.6%, the Κ_Ⅲ phase increased and Al₄Cu₉ phase decreased in the alloy. When the mass fraction of iron was 3.2%, Al₄Cu₉ phase further decreased, and Κ_Ⅰ and Κ_Ⅱ phases were precipitated in the alloy. When the iron content continued to increase, the Al₄Cu₉ phase disappeared, Κ_Ⅰ phase increased while Κ_Ⅲ phase decreased. With increasing iron content, the sintered density of the alloy decreased, the hardness decreased first then increased and then decreased, and reached the maximum with iron mass fraction of 3.2%. The yield strength of the alloy fluctuated with increasing iron content, and reached the maximum when the mass fraction of iron was 4.8%.