Considerations in Designing Alloys for Laser-Powder Bed Fusion Additive Manufacturing

This work identifies alloy terminal freezing range, columnar growth, grain coarsening, liquid availability towards the terminal stage of solidification, and segregation towards boundaries as primary factors affecting the hot-cracking susceptibility of fusion-based additive manufacturing (F-BAM) processed alloys. Additionally, an integrated computational materials engineering (ICME)-based approach has been formulated to design novel Al alloys, and high entropy alloys for F-BAM processing. The ICME-based approach has led to heterogeneous nucleation-induced grain refinement, terminal eutectic solidification-enabled liquid availability, and segregation-induced coalescence of solidification boundaries during laser-powder bed fusion (L-PBF) processing. In addition to exhibiting a wide crack-free L-PBF processing window, the designed alloys exhibited microstructural heterogeneity and hierarchy (MHH), and thus could leverage the unique process dynamics of L-PBF to produce a fine-tunable MHH and mechanical behavior. Furthermore, alloy chemistry-based fine tuning of the stacking fault energy has led to transformative damage tolerant alloys. Such alloys can shield defects stemming from the stochastic powder bed in L-PBF, and consequently can prevent catastrophic failure despite the solidification defects. A modified materials systems approach that explicitly includes alloy chemistry as a means to modify the printability, properties and performance with F-BAM is also presented. Overall, this work is expected to facilitate application specific manufacture with …
Date: May 2022
Creator: Thapliyal, Saket
System: The UNT Digital Library