Ongoing Challenges of Laser-Based Powder Bed Fusion Processing of Al Alloys and Potential Solutions from the Literature—A Review

Abstract

Their high strength-to-weight ratio, good corrosion resistance and excellent thermal and electrical conductivity have exponentially increased the interest in aluminium alloys in the context of laser-based powder bed fusion (PBF-LB/M) production. Although Al-based alloys are the third most investigated category of alloys in the literature and the second most used in industry, their processing by PBF-LB/M is often hampered by their considerable solidification shrinkage, tendency to oxidation, high laser reflectivity and poor powder flowability. For these reasons, high-strength Al-based alloys traditionally processed by conventional procedures have often proved to be unprintable with additive technology, so the design and development of new tailored Al-based alloys for PBF-LB/M production is necessary. The aim of the present work is to explore all the challenges encountered before, during and after the PBF-LB/M processing of Al-based alloys, in order to critically analyse the solutions proposed in the literature and suggest new approaches for addressing unsolved problems. The analysis covers the critical aspects in the literature as well as industrial needs, industrial patents published to date and possible future developments in the additive market.

In-situ monitoring of the material composition in PBF-LB via optical emission spectroscopy

“…[14] To mitigate these negative effects, various strategies can be employed, such as optimizing laser parameters, using an appropriate shielding gas, and controlling the process environment to reduce plasma formation and spatters. [4,10] Additionally, advanced monitoring and control systems can be employed to detect and correct any deviations in the process, ensuring the quality and reliability of the final part.…”

“…[1,2] In this process, a laser beam melts the metal powder feedstock to obtain dense components after solidification. [3] However, the high solidification rates, in the range of 10 5 K/s [4], can lead to microcracks, non-equilibrium structures with phase segregation, and columnar grain growth, which typically affect the material strength. [5] Therefore, the quality of PBF-LB/M-manufactured products heavily depends on the manufacturing process.…”

Effect of Cu Content on the PBF-LB/M Processing of the Promising Al-Si-Cu-Mg Composition

“…In addition, a limited presence of satellites is required to ensure a proper powder flowability and, thus, to achieve a higher quality of the powder bed. A key role in the packing and flow properties of powders is also played by the PSD, which must find the right balance between fine and coarse particle fractions [36]. To verify the characteristics of the three gas-atomized systems, powders in the 20-63 µm fraction were observed by SEM.…”

Study on Flowability Regulation of Vacuum Gas-Atomized Fe-Cr-Ni-W-B Spherical Powder

“…Fe-W-B system materials are a novel ternary boride with a TiNiSi crystal structure and a high content of W and B (73.4% and 4.3% wt%, respectively) [ 1 ]; these materials exhibit a wide range of unusual physical and chemical properties at elevated temperatures [ 2 , 3 ]. These fascinating features open a wide range of possible applications for Fe-W-B, including nuclear shielding, microwires, petrochemicals, corrosion-resistant coating, and wear-resistant materials [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”