Microstructure and properties of Al6Cu2Ni gearbox with TIG additive for repairing casting defects

The background of this paper is a new type of heat-resistant alloy for aviation. In allusion to the defects in Al6Cu2Ni alloy castings, the defects were removed by milling and repaired by arc adding. The results show that the grain distribution in the weld is uniform and there is no delamination. The orientation of the grains in the weld is disordered and the crystal structure is stable with a large angle. The composition of the second phase in the weld metal is the same as that of the base metal, and no new phase is formed. Al3CuNi, Al7Cu4Ni, and Al2Cu were formed and concentrated at the grain boundary, and AL3M existed in micron size. The tensile strength at room temperature is 213.8 MPa, the yield strength is 159 MPa, the elongation is 1.65%, and the tensile property is 93% of the base metal. There are a lot of cleavage surfaces on the fracture surface, which is a typical brittle fracture.