Wire arc additive manufacturing of Ni-Al intermetallic compounds through synchronous wire-powder feeding

Abstract

Here we proposed a new method to solve the difficulty existing in wire arc additive manufacturing of Ni-Al intermetallic compounds (IMCs), i.e., no welding wire available owing to the brittle fracture occurring in wire drawing. A synchronous wire-powder hybrid manufacturing by using Ni wire as forming material and auxiliary filling Al powder was employed. Based on the optimized feeding rate of Al powder (VAl) at 0.77 g/min, the deposited microstructure including γ-Ni matrix and grid-like γ'-Ni3Al/γ-Ni was obtained, which increased the ultimate tensile strength by 8% while maintaining the elongation by 90 % compared with the deposited thin-wall without filling Al powder. When the VAl increased to 1.39 g/min, the deposited microstructure remained unchanged, but the distribution of precipitated γ'-Ni3Al/γ-Ni transferred to block-like shape due to its increasing average content from 18.22 % to 50.48 %. It then directly resulted in cracks at the bead surface after the deposition height reached 11 mm. This study mainly investigated the effects of adding amount of Al powder on microstructure transformation of deposited Ni-Al IMCs, as well as its influence mechanisms on mechanical properties and cracking tendency.