Research on plasma arc additive manufacturing of Inconel 625 Ni–Cu functionally graded materials

In this work, a plasma arc additive manufacturing technique with a double-wire feedback mechanism was used to manufacture Inconel 625 Ni–Cu functionally graded materials. The microstructure, mechanical properties and corrosion properties of the deposited alloy were evaluated. Microstructure observation and tensile testing of parts with different element contents indicated that functionally graded materials were obtained through the manufacturing process. The results have shown that due to the very high growth restriction factor Q of Cu, its addition can increase the constitutional supercooling zone, resulting in a decrease in columnar and dendrites and an increase in equiaxed crystals in the Inconel 625 Ni–Cu functionally graded material, as well as changing the Schmid factor (SF) distribution. The tensile strength and ductility of the Inconel 625 Ni–Cu functionally graded materials increased with increasing Cu content, while the corrosion resistance of the alloy decreased with increasing Cu content during electrochemical corrosion tests.