Additively Manufactured High-Strength Aluminum Alloys: A Review

Abstract

This chapter summarizes the recent advances in additive manufacturing of high-strength aluminum alloys, the challenges of printability, and defects in their builds. It further intends to provide an overview of the state of the art by outlining potential strategies for the fabrication of bulk products using these alloys without cracking. These strategies include identifying a suitable processing window of additive manufacturing using metallic powders of conventional high-strength aluminum alloys, pre-alloying the powders, and developing advanced aluminum-based composites with reinforcements introduced either by in situ or ex situ methods. The resulting microstructures and the relationship between these alloys’ microstructure and mechanical properties have been discussed. Since post-processing is inevitable in several critical applications, the chapter concludes with a brief account of post-manufacturing heat treatment processes of additively manufactured aluminum alloys.

Heat Treatments for Minimization of Residual Stresses and Maximization of Tensile Strengths of Scalmalloy® Processed via Directed Energy Deposition

“…Most structural parts are fabricated using traditional methods, such as casting, forging, extrusion, and powder metallurgy. Aluminum alloys are characterized by high strength-to-weight and stiffness-to-weight ratios [ 1 ], making them attractive for use in near-net-shape processes; however, these alloys also exhibit poor laser absorptivity due to high reflectivity, high thermal conductivity, and a strong tendency towards oxide formation [ 2 , 3 ]. These complications make aluminum alloys difficult to fabricate using AM processes.…”

“…In addition to the inherent properties of aluminum and its alloys, AM processing of these high-strength alloys is plagued by unique defect mechanisms. High-strength aluminum alloys, such as the commonly used Al7075 and Al6061, have a large mushy zone or solidification range [ 2 , 4 ]. When fabricated via AM, the large solidification range promotes cracking and poor mechanical behavior [ 4 , 5 , 6 ].…”