Scandium Canada Ltd V.SCD

Good progress in Sc-Al Alloy 3D Printing Options

[ScandiumPower]

Abstract

Laser powder bed fusion (LPBF) is one of the typical additive manufacturing techniques that enables the fabrication of complex-shaped structures with great freedom of design. Due to the challenges encountered in LPBF processing of Al alloys, most studies have focused on AlSi alloys which are much easier to process but are not inherently designed for high-strength applications. In recent years, however, significant progress has been made to develop Sc-containing Al alloys that are designed specifically for LPBF production. These alloys display excellent processability and superior mechanical properties that open up a range of possible applications in industries that require high specific strength, good thermal stability, and increased functionality. As such, this paper reviews the available literature on how Sc additions influence the microstructure and properties of Al alloys when processed via LPBF and thus, aims to shed light on the considerations that have been made to achieve remarkable material consolidation alongside excellent mechanical properties, with the latter achieved through a high degree of Sc supersaturation and a great potential for nanoprecipitation.

Summary and outlook

The precipitation-strengthened Sc-containing Al alloys have shown excellent LPBF printability coupled with high strength capabilities achievable with an industrially favorable single-step post-processing treatment. The alloy design rationale lies in the use of L12-type precipitates to promote heterogeneous nucleation during rapid solidification to mitigate crack formation. The rapid solidification in the LPBF process is innovatively exploited to place large amounts of Sc into the solution than is possible by conventional processing. The generated metastable microstructure effectively fosters multiple strengthening mechanisms. Even though Sc is comparably costly, the high specific strength of Sc-containing Al parts enables weight reduction. In addition, the near-net shape capabilities of LPBF result in a buy-to-fly ratio close to 1, i.e., negligible material waste. Both factors can make the use of Sc more sensible for high-value components.

https://www.sciencedirect.com/science/article/pii/S1005030223000385