增材制造中高强铝合金的缺陷 与力学性能研究进展

Aluminum alloy is an important light metal structural material, which has been widely used in aerospace and transportation industries. Wrought aluminum alloys generally require extrusion, rolling or forging after casting to be processed into finished products. However, this conventional casting-deforming-cutting subtractivc manufacturing route has become increasingly difficult to meet the manufacturing demands of high efficiency and environmental sustainability. As an emerging manufacturing method, additive manufacturing (AM) provides brand-new possibilities for the manufacturing of aluminum alloys by depositing subsequent layers based on digital drawing files to make three-dimensional objects. However, most aluminum alloys arc suffering from the various defect issues due to the manufacturing characteristics of laser-based AM processes and several intrinsic properties of aluminum alloys, which impair their mechanical properties and limit their industrial applications. Various defects and corresponding causes in additively manufactured medium- and high-strength aluminum alloys were reviewed in this paper. In addition, latest researches on eliminating defects and thus improving mechanical properties of AM aluminum alloys were summarized from three aspects: process parameter optimization, alloy composition optimization and nucleant agent addition. This work demonstrates that processing parameter and alloy composition should be regulated synergistically to improve the microstructures and mechanical properties of additivcly manufactured medium- and high-strength aluminum alloy, and the optimal heat treatment should also be investigated.