Additive Manufacturing: Materials Design and Alloy Development V – Design Fundamentals: Aluminum Alloys II
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Integrated Computational Materials Engineering Committee
Program Organizers: Behrang Poorganji, Morf3d; Hunter Martin, HRL Laboratories LLC; James Saal, Citrine Informatics; Jiadong Gong, Questek Innovations LLC; Orlando Rios, University of Tennessee; Atieh Moridi, Cornell University

Tuesday 2:30 PM
March 21, 2023
Room: 24C
Location: SDCC

Session Chair: Orlando Rios, UTK


2:30 PM  Invited
Hypereutectic Al-Si-Cu Alloy for Laser Powder Bed Fusion: Andrew Bobel1; Yoojin Kim2; Lee Casalena3; Anil Sachdev1; 1General Motors Corporation; 2Populus Group; 3Thermo Fisher Scientific
    A hypereutectic Al-Si-Cu alloy was designed and evaluated for high strength and elevated temperature automotive applications using laser powder bed fusion (LPBF). A computational design approach combined with meltspinning experiments enabled rapid alloy development and down selection for atomization. Parameter development for the Al-Si-Cu alloy revealed a large printability range, between 1-3 J/mm2, with consolidation greater than 99.97% density. Electron backscatter diffraction (EBSD) analysis revealed an isotropic microstructure with no texturing, and transmission electron microscopy (TEM) revealed nano-Si particle formation and Al2Cu Theta-phase precipitation. Elevated uniaxial tensile properties and fully reversed (R=-1) tension-compression high cycle fatigue (1e7) show superior strengths compared to the commercial AlSi10Mg alloy across all test temperatures up to 300C.

3:00 PM  
A Powder-free Methodology to Develop New High-strength Al-alloys with Unique Microstructures and Mechanical Properties: Giuseppe Del Guercio1; David McCartney1; Christopher Tuck1; Marco Simonelli1; 1University of Nottingham
    Laser-powder bed fusion (L-PBF) has opened new opportunities to design and process novel advanced materials with unique microstructures. However, the development of high-strength aluminium (Al) alloys is hampered by the occurrence of detrimental hot-cracking phenomena and limited availability of custom powders. In this talk, we design a custom Al-Cu-Ni alloy characterized by both optimized strength and processability with the aid of a powder-free methodology that predicts the cracking behaviour of custom compositions pairing predictive tools based on the CALPHAD approach and established hot cracking criteria. The calculations are experimentally validated via a detailed microstructural characterization and mechanical behaviour analysis of arc melted buttons of compositions remelted under L-PBF regimes. After the identification of the optimum composition, the alloy is gas atomized, printed, and fully characterized. The results highlight the need to diverge from traditional materials to exploit the merits of the new alloy design spaces opened by metal 3D printing.

3:20 PM  
Microstructure and Mechanical Properties of Near-eutectic Al-Ce-Ni-Fe Alloys Produced by Laser Powder-bed Fusion: Tiffany Wu1; Amit Shyam2; Alex Plotkowski2; David Dunand1; 1Northwestern University; 2Oak Ridge National Laboratory
    Additively manufactured aluminum alloys offer an opportunity to achieve mechanical performance at elevated temperatures superior to conventional processing routes, and therefore, may be able to replace denser alloys. Yet, the selection on processible additive manufactured aluminum alloys is currently limited. Eutectic-based aluminum alloys are good candidates for high-temperature applications, as they show good processibility (hot-tearing resistance) and strengthening (load transfer to large volume fraction of eutectic formed during solidification). In this work, a new quaternary near-eutectic Al-6.5Ce-3.2Ni-0.8Fe (wt.%) was fabricated via laser powder-bed fusion. We show how different microstructures impact tensile and creep properties up to 400°C. Coarsening resistance of the eutectic phases is discussed with microhardness and microstructure evolution during aging. By comparing with a cast alloy of the same composition, we demonstrate the effect of non-equilibrium conditions, achieved via additive manufacturing, on eutectic morphology and phases formation, and therefore on the mechanical response of the alloy.

3:40 PM  
Microstructure and High-temperature Mechanical Properties of a Novel Al-Ni-Fe-Zr Alloy Processed by Laser Powder Bed Fusion: Joshua Dorn1; Hyeji Park2; Joseph Croteau1; Nhon Vo1; David Dunand2; 1NanoAl LLC; 2Northwestern University
    The microstructural evolution of a novel, near-eutectic Al-Ni-Fe-Zr alloy, processed by laser powder-bed fusion (LPBF) and subsequently heat-treated, is investigated. A highly heterogeneous grain structure is observed, consisting of micron-sized cellular equiaxed grains at melt pool boundaries and coarser eutectic columnar grains in the melt pool interiors. After heat treatment in a range of 250 to 350 °C, the interconnected fine Al9FeNi eutectic phase, formed under rapid solidification conditions during LPBF processing, coarsens and fragments. High mechanical properties at both ambient and elevated temperatures are observed, as compared to a LPBF AlSi10Mg alloy. Compressive creep testing at 300°C shows that diffusional creep dominates at low stresses and dislocation creep at high stresses, with the presence of a threshold stress. Relationships between microstructure evolution and creep properties are discussed.

4:00 PM Break

4:20 PM  
Physics-constrained, Inverse Design of High-temperature, High-strength, Creep-resistant Printable Al Alloys Using Machine Learning Methods: S. Mohadeseh Taheri-Mousavi1; 1Carnegie Mellon University
    Aluminum alloys that exhibit high strength and creep resistance at high temperatures can be our next-generation fan blades of jet engines and pistons of combustion engines. However, additive manufacturing (AM) of these alloys is traditionally challenging due to the presence of hot cracking. We demonstrate a physics-constrained, inverse design framework with data generated from integrated computational materials engineering (ICME) techniques to explore the compositional space of Al-Zr-Er-Y-Yb-Ni, and identify an optimal alloy composition achieving maximum predicted strength at a temperature of 250ºC. Using only 40 sampling data with our most efficient machine learning algorithm (neural network), we predict a microstructure with 3.5X higher stability of nanoscale hardening phases than a state-of-the-art printable Al-alloy. The mechanical testing and microstructural analysis of the 3D-printed optimal composition validated the predictions. The combined numerical and experimental techniques provide an efficient and robust pathway for transformative future alloy design by various manufacturing techniques, especially AM.

4:40 PM  
Laser Powder Bed Fusion of Nanoparticles-Enabled High-Zinc Al-Zn-Mg-Cu Alloys: Tianqi Zheng1; Shiqi Zheng1; Jingke Liu1; Bingbing Li2; Xiaochun Li1; 1University of California, Los Angeles; 2California State University, Northridge
    The high-zinc Al-Zn-Mg-Cu alloys offers highest strength among aluminum alloys due to their high fraction of strengthening precipitates. However, high-zinc Al-Zn-Mg-Cu alloys are susceptible to hot-cracking and zinc/magnesium vaporization, thus difficult to be processed by Laser Powder Bed Fusion (LPBF). Here, specially designed high-zinc Al-Zn-Mg-Cu powders containing 11.63 wt% Zn with internally dispersed TiC nanoparticles, produced by gas atomization, are used for LPBF. Through parameter optimization, we have been able to print the parts with low porosity (<1%) and fine grain structures, offering an ultimate tensile strength (UTS) up to 520 MPa in the as-printed state. After T6 heat treatment, the samples can deliver a yield strength of 723 MPa, UTS of 770 MPa and ductility over 6%, which are the highest strengths among all 3D-printable aluminum alloys. The nanoparticle approach is very effective in enabling high quality printing of ultrahigh performance aluminum alloys.

5:00 PM  
Microstructure and Mechanical Properties of Al-5Mg2Si-2Mg Alloy Processed by Laser Powder Bed Fusion: Shouxun Ji1; Hailin Yang2; 1Brunel University London; 2Central South University
    In this work, we use a new Al-5Mg2Si-2Mg alloy to produce high-strength and ductile for laser powder bed fusion (LPBF) process. The as-LPBFed alloy is found to deliver much less hot cracks and defects, and excellent mechanical property, which include 452 MPa of UTS, 295 MPa of yield strength (YS) and 9.3% of elongation. The as-LPBFed alloy is featured by the significantly refined cellular microstructures, including the primary α-Al and the eutectic Mg2Si phases and α-AlFeMnSi phase. After ageing at 180 ºC for 3.5 h, the ultrafine in-situ Mg2Si particles are formed inside the cell. The YS of 377 MPa, UTS of 488 MPa and elongation of 9.6 % are achieved. The excellent mechanical properties and processability are attributed to (a) the reduced solidification range, (b) the refined α-Al grains, (c) the formation of supersaturated solid solution, and (d) the precipitation of nanophases.

5:20 PM  
In-situ Reactive Printing of Aluminum Matrix Composite with Ultra-high Volume Fraction Reinforcement: Chenxi Tian1; Atieh Moridi1; 1Cornell University
    Aluminum’s large freezing range and high reflectivity greatly reduce its compatibility with AM. This hinders development of laser-based aluminum AM and deteriorates the existing lack of lightweight structural materials in the intermediate temperature range. Aluminum matrix composites (AMCs) have great potential as thermally stable lightweight structural materials. However, it's fabrication largely uses conventional methods, achieving only moderate volume fraction of reinforcement while having limited part complexity. In-situ reactive printing (IRP) is adopted as a novel method, harnessing the reaction product of dissimilar elemental powder mix to fabricate AMC with an ultra-high volume fraction of intermetallic reinforcement. In this study, the effect of titanium addition to elemental aluminum feedstock powder is systematically studied on different aspects including material processability, microstructural features and mechanical performances. The results show that IRP can overcome the incompatibility between AM and aluminum and produce AMC with exceptional volume fraction of reinforcements when compared to existing counterparts.