Preparation of Ni–Al intermetallic compounds by plasma arc melting deposition through double-wire feeding

Double-wire plasma arc melting deposition was used to fabricated Ni–Al intermetallic compounds by the optimization of feeding position of Ni and Al wires with big difference in melting point. The proposed double-wire synchronous feeding method cleverly solved the problem that the weld bead could not be effectively formed due to the preferential melting of Al wire with low melting point. After the optimization of double-wire feeding position, the effects of heat input on the microstructure uniformity of deposited Ni–Al intermetallic compounds were also studied. It was found that with the increase of heat input from 2.453 to 3.143 kJ/mm, the deposited microstructures transferred from M-NiAl + Ni3Al to M-NiAl+γ′-Ni3Al/γ-Ni, and the amount of γ′-Ni3Al/γ-Ni was increased and became uniformly distributed. These combined improvements benefited to reduce the difference in the microhardness from top to bottom areas of deposited Ni–Al intermetallic compounds. The related results provide new ideas for the high-efficiency and low-cost manufacturing of intermetallic compounds or other difficult-to-deposit metals.