Additive Manufacturing: Materials Design and Alloy Development IV: Rapid Development: Aluminum Alloys
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; Orlando Rios, University of Tennessee; Atieh Moridi, Cornell University; Jiadong Gong, Questek Innovations LLC
Tuesday 2:30 PM
March 1, 2022
Room: 261A
Location: Anaheim Convention Center
Session Chair: Hunter Martin, HRL
2:30 PM Invited
Alloy Design for High Temperature Aluminum: Darby Laplant1; John Martin1; 1HRL Laboratories, LLC
Additive manufacturing has broadened the scope for alloy design, specifically for high temperature aluminum alloys, by employing a faster solidification pathway than traditional casting. Current conventional high temperature aluminum alloys rely on the introduction of high cost elements or the use of rapid solidification to form metastable high temperature strengthening phases. These materials are less feasible for applications needing cost efficiency or complex geometries, and aren’t always adaptable to 3D printing due to susceptibility to solidification cracking. Leveraging HRL Laboratories’ functionalization technique to quickly screen compositions, we have produced a new aluminum alloy consisting of Cr and Zr at concentrations optimized for the unique processing conditions in additive manufacturing. This talk will highlight recent data and analysis that showcases this alloy’s high strength and temperature stability above 300C, with comparisons to current aluminum alloy data.
3:00 PM Invited
Alloy Design and Rapid Development of New Ternary and Quaternary Al-Ce-based Alloys for Additive Manufacturing: Hunter Henderson1; Aurelien Perron1; Emily Moore1; Scott McCall1; Ryan Ott2; Orlando Rios3; 1Lawrence Livermore National Laboratory; 2Ames Laboratory; 3University of Tennessee-Knoxville
The Al-Ce alloy system offers new opportunities to design alloys specifically for Selective Laser Melting Additive Manufacturing. The inherent rapid solidification of the process induces nanoscale structures that are extremely resistant to thermal coarsening, achieving high strength that is resistant to degradation. Here we will highlight recent work within the Critical Materials Institute exploring additional alloying additions like Mg, Ni, and Fe to Al-Ce through directed energy deposition combinatorial synthesis and rapid property assessment. Results are correlated to thermodynamic predictions of solidification pathway and phase distribution. It is found that additional alloying elements can induce complex changes in phase distribution and strength, both of which are also a function of solidification rate. Promising Al-Ce ternary, quaternary, and quinary alloy candidates for particular applications will also be discussed.
3:30 PM
A Modified 7068 Aluminum Alloy Designed for Laser Powder Bed Fusion: Brandon Fields1; Benjamin MacDonald1; Xiaochun Li2; Lorenzo Valdevit1; Diran Apelian1; 1University of California, Irvine; 2University of California, Los Angeles
Many additively manufactured alloys exhibit higher strengths when compared to compositionally identical alloys processed via conventional processing routes. However, this enhancement is not observed in 7xxx series Aluminum. These alloys exhibit two complications when printed via Laser-Powder-Bed-Fusion (LPBF): significant evaporation of strengthening elements from the melt-pool and crack formation due to hot tearing during solidification. To address these issues, we have designed and developed a modified Al-7068 alloy with increased alloying accounting for evaporation; additionally, TiC nanoparticles dispersed within the powder promote heterogenous nucleation and restrict grain growth, thus avoiding hot tearing. Printing parameters are optimized for minimum porosity. Trends in alloying elements’ evaporation with increased laser energy density are quantified using inductively-coupled-plasma mass-spectrometry. The microstructure and mechanical behavior in as-built and T6-heat-treated conditions are characterized using x-ray diffraction and scanning electron microscopy. The experimental work was complemented by CALPHAD phase stability calculations. The results will be presented and discussed.
3:50 PM
An Advanced High-performance Aluminum Alloy Designed for Wire-arc Additive Manufacturing: Thomas Klein1; Martin Schnall1; Rudolf Gradinger1; Stephan Ucsnik1; 1LKR Light Metals Technologies Ranshofen
The processing conditions prevailing during wire-arc additive manufacturing (WAAM) are challenging for the alloys used on numerous fronts. High-performance aluminum alloys are particularly demanding. For example, 2xxx and 7xxx are prone to hot-cracking. While an overwhelming body of literature is available on commercial alloys, there is no scientific reason for optimum suitability of these alloys for WAAM. Therefore, we present developments on a novel alloying strategy with the potential of high strength together with sufficient ductility. For this purpose, the Mg/Zn ratio in the system Al-Mg-Zn has adapted to improve the processability and the mechanical properties were tailored by microalloying additions. Specimens manufactured were free of cracks with a homogeneous microstructure. After optimization of the heat treatment a yield strength of ~395 MPa and a fracture strength of ~470 MPa was reached at a fracture elongation of ~5%. The strength values are comparable to high-performance wrought or forged aluminum products.
4:10 PM Break
4:25 PM
Laser Powder Bed Fusion of Novel Aluminum Alloy: Glenn Bean1; 1The Aerospace Corporation
Additive manufacturing technologies have been rapidly adopted by the aerospace industry and aluminum alloys are critical for launch and spacecraft applications. Current printing has been limited to lower-strength Al-Si-Mg due to its printability. However, compared with traditional 7000-series engineering alloys, Al-Si-Mg has roughly half the strength. Research focused on process development, printing, characterization, and applications for a 7000-series alloy designed for AM, with superior mechanical properties, has been conducted in collaboration with commercial partners. Thermal and chemical analysis, CALPHAD tools, and mechanical testing have been utilized to characterize, develop heat treatments, and improve AM processing for this novel aluminum alloy. Physical print characterization is used in conjunction with computational software to simulate and understand the build process and precipitation strengthening behavior. Further development of these tools can both reduce experimental time and optimization for rapid insertion of high-performance AM aluminum alloys into aerospace structures.
4:45 PM
Selective Laser Melting of Novel 7075 Aluminum Alloy with Internally Dispersed Nanoparticles: Tianqi Zheng1; Shuaihang Pan1; Bingbing Li2; Xiaochun Li1; 1University of California, Los Angeles; 2California State University, Northridge
Due to its high performance, 7075 aluminum alloy has been widely used in aerospace and automobile industries. Selective laser melting (SLM) recently emerged as a promising platform to fabricate metallic components with complex structures. SLM has been successful in manufacturing aluminum alloys such as Al-Si-Mg alloys. However, SLM of high strength aluminum 7075 alloys is difficult to control for its tendency of hot cracking and elemental. Here, specially designed 7075 aluminum alloy powders with internally dispersed TiC nanoparticles are produced by gas atomization. These novel powders have been successfully laser printed to form parts with homogenous globular grains and little porosity, delivering a tensile strength of up to 550 MPa and ductility over 6.5% in as-printed state. After T6 heat treatment, the printed parts can offer a tensile strength of about 650 MPa. TiC nanoparticles play a crucial role in refinement and growth restriction of grains while eliminating hot cracks.
5:05 PM
Towards New High-strength Al-alloys Specifically Designed for L-PBF: Giuseppe Del Guercio1; David McCartney1; Nesma Aboulkhair1; Christopher Tuck1; Marco Simonelli1; 1University of Nottingham
Laser-powder bed fusion (L-PBF) has opened new opportunities to process advanced materials with unique microstructures arising from the rapid solidification conditions imposed during the printing process. However, the development of high-strength aluminium (Al) alloys remains limited due to the occurrence of detrimental hot-cracks and scarse availability of custom powders. In this talk, we propose a comprehensive methodology to design and develop novel crack-free high-strength Al-alloys tailored for the L-PBF process. The cracking behaviour of custom compositions is predicted by coupling established models for hot cracking with solidification gradients evaluated using the CALPHAD approach. The calculations are experimentally validated via a detailed microstructural characterisation of arc melted buttons of custom compositions remelted under L-PBF processing conditions. We then show how this method was used to isolate a novel Al-Cu-Ni alloy that, whilst minimising hot-crack-susceptibility, possesses excellent strength, measured indirectly from hardness tests. Preliminary L-PBF processability and tensile performance is then presented.
5:25 PM
Thermodynamic Modeling to Design New Al-Ce Alloys: Emily Moore1; Hunter Henderson1; Orlando Rios2; Scott McCall1; David Weiss3; Aurélien Perron1; 1Lawrence Livermore National Laboratory; 2University of Tennessee at Knoxville; 3Eck Industries
The development of new Aluminum alloys to include cerium has been investigated to improve the coproduction of mining light rare-earth elements. Ce has been shown to greatly impact the strength of Al-alloys and enhance mechanical properties. With the addition of multiple alloying elements, the strengthening mechanisms may be altered. It is therefore key to understand the phase stability across multicomponent systems to avoid the precipitation of phases that may harm the mechanical behavior of the material. Thermochemical modeling using the CALPHAD method (CALculation of PHAse Diagram) to address the Al-Ce-Cu-Fe-La-Mg-Mn-Ni-Si-Zn-Zr system is presented. The model is applied to design new alloys with within specified composition ranges and include relevant phases that are empirically known to provide strengthening properties. Prepared by LLNL under Contract DE-AC52-07NA27344. Research supported by CMI, an Energy Innovation Hub funded by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.