Additive Manufacturing: Materials Design and Alloy Development V – Design Fundamentals: Aluminum Alloys I
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 8:00 AM
March 21, 2023
Room: 24C
Location: SDCC
Session Chair: Hunter Martin, HRL
8:00 AM Invited
Al-Ce Alloys for Additive Manufacturing: Ryan Ott1; Seungjin Nam1; Nicolas Argibay1; Hunter Henderson2; Orlando Rios3; Scott McCall2; 1Ames National Laboratory (USDOE); 2Lawrence Livermore National Laboratory; 3University of Tennessee Knoxville
Developing alloys for Additive Manufacturing (AM) presents many challenges compared to more traditional processing methods such as casting. Specifically, exploring large composition space requires various feedstock alloys (e.g., powders) that can be expensive and time consuming to produce. Another challenge is mapping out processing-structure-property relationships typically requires a large number of bulk samples to be printed. We have used directed energy deposition (DED) to rapidly synthesize Al alloy libraries over a wide range of compositions. The relatively small samples (~ 5 x 5 x 5 mm3) are ideal for instrumented scratch testing, which unlike various hardness testing methods (e.g., Vickers) can provide greater insight into the bulk mechanical response including ductility and fracture toughness. Using this combined approach, we have rapidly identified Al alloy compositions that are both compatible with laser-based AM synthesis and show excellent strength and ductility.
8:30 AM
Design of an Aluminum Alloy Based on Stable Nanoparticles for Eliminating Process Instability in Laser Metal Additive Manufacturing: Minglei Qu1; Qilin Guo1; Luis Izet Escano1; Ali Nabaa1; S. Mohammad H. Hojjatzadeh1; Lianyi Chen1; 1University of Wisconsin-Madison
The process instabilities intrinsic to the localized laser-powder bed interaction cause the formation of various defects in laser powder bed fusion additive manufacturing process. Conventional material design strategy for additive manufacturing relies on modifying the element composition based on the phase diagram to enhance the strength or ductility without considering the intrinsic process instability problem. Here we report a unique material design method of adding TiC nanoparticles in Al6061 powders to control the intrinsic process instability and eliminate the large spatters, resulting in 3D printing of defect lean sample with good consistency and enhanced properties. The nanoparticle-induced elimination of large spatters is attributed to: (1) nanoparticle-enabled control of molten pool fluctuation eliminates the liquid breakup induced large spatters; (2) nanoparticle-enabled control of the liquid droplet coalescence eliminates liquid droplet colliding induced large spatters. Our research may guide the development of feedstock material design to achieve defect lean metal additive manufacturing.
8:50 AM
Finding “Printing” Alloys: A New Category of Aluminum(-Cerium) Alloys in an Untapped Composition Space: Alfred Amon1; Seungjin Nam2; Emily Moore1; Hunter Henderson1; Orlando Rios3; Ryan Ott2; Scott McCall1; 1Lawrence Livermore National Laboratory; 2Ames Laboratory; 3University of Tennessee Knoxville
Aluminum alloys experience aggressive development for additive manufacturing. The vast amount of work has been dedicated to the adaptation of traditional heat-treatable, near-eutectic Al-Si casting alloys such as AlSi12, AlSi10Mg, AlSi9Cu3, A6061 or A356. Rapid solidification during the AM process results in fine-grained microstructures and warps the solidification pathways in a drastic and unpredictable manner. While casting alloys outperform compositions for wrought processing, they are not optimal, raising the need for a new category of “printing” alloys. We have investigated the suitability of as-cast Al-Ce-Mg alloys with high Fe and Ni content for SLM processing. Combination of target prefabrication by DED and consequent laser surface traces enable a high-throughput composition screening of alloys with unconventionally high transition metal content. A microstructure-hardness mapping enabled pre-selection of composition and processing parameters. While discovering new alloys with high hardness, this study paves the way for unconventional alloy design approaches in the AM space.
9:10 AM
Laser Powder Bed Fusion of Al-Ce Alloys: Holden Hyer1; Abhishek Mehta1; Le Zhou2; Brandon McWilliams3; Kyu Cho3; Yongho Sohn1; 1University of Central Florida; 2Marquette University; 3DEVCOM Army Research Laboratory
This study expands on previous work performed with the highly processable Al-10Ce alloy, by investigating the LPBF processing, microstructure, and mechanical performance of ternary Al-Ce-Mg towards a high strength, high temperature alloy. Alloy hardness and density were found to be a function of the varying degree of Mg in solid solution and the amount vaporized during laser exposure, but near full density was achieved with two parameter combinations at high (350 W) and low (200 W) laser power. The grain structure was found to be bimodal at 200 W, and equiaxed at 350 W. Moreover, the tensile strength and hardness were larger with use of the 200 W, but ductility increased with use of the 350 W. A fine (<1 µm) sub-grain cellular structure, with intermetallic Al11Ce3 ribbons was found located at the intercellular boundaries, contributing to the strength of the alloy through Orowan dislocation looping and Hall-Petch boundary strengthening.
9:30 AM Break
9:50 AM
Impact of Starting Particle Content and Laser Powder Bed Fusion Processing on Microstructure and Material Properties in A6061-RAM Alloys: Chloe Johnson1; Michael Kaufman2; Adam Polizzi1; Jeremy Iten1; Amy Clarke2; 1Elementum 3D; 2Colorado School of Mines
Aluminum alloys are excellent candidates for light-weighting using laser powder bed fusion additive manufacturing (AM), which can produce parts with complex cooling channels, allowing lower operating temperature alloys to withstand higher temperatures. However, aluminum alloys are difficult to print, having a high thermal conductivity, low absorptivity, and large solidification range, which can cause solidification cracking during the final stages of solidification. Reactive additive manufacturing (RAM) alloys, which contain micron-scale particles that undergo a thermodynamically favorable reaction in the melt during AM to generate product, submicron inoculant particles, present a method to fully refine the grain structure and prevent solidification cracking in AM aluminum alloys. Partially dissolved additive particles and submicron inoculants also give RAM alloys composite properties. The types and amount of reactive particles in RAM powder feedstocks allow for tailoring of material properties and performance to different applications and generate unique microstructures based on RAM content and AM processing.
10:10 AM Cancelled
Designing High-Strength Aluminum and Superalloys for Laser Powder Bed Fusion: Analyzing Cases of Success and Failure: Marcus Lam1; 1Monash University
High-strength aluminum and superalloys are particularly challenging for Laser powder bed fusion (LPBF) process due to their low ductilities and high crack susceptibilities. Designing or modifying the alloy specifically for the LPBF process is in many cases necessary. In this presentation, we are presenting our experience in analyzing and solving the material issues related to a few new and modified Al and Ni alloys designed for LPBF. Several Al-Sc, Al-Zn aluminum alloys and high-γ' nickel-based superalloys will be covered. Some of the metallurgical topics will be discussed include the exploitation of supersaturation in LPBF, inequilibrium phase formation, LPBF crack susceptibly evaluation and grain size effect. Other issues related to the development of LPBF-specific alloys include sample’s size/type, the consideration of available processing conditions and the ductility requirement for components. We aim to highlight in this presentation the importance of both the metallurgical fundamentals and application considerations in developing LPBF-specific alloys.
10:30 AM
Using θ' Interfaces as Templates for Planar L12 Precipitation in Additively Manufactured AlCuMnZr Alloys: Jonathan Poplawsky1; Richard Michi1; Lawrence Allard1; Sumit Bahl1; Dongwon Shin1; Alex Plotkowski1; Amit Shyam1; 1Oak Ridge National Laboratory
Mn and Zr microsolute additions stabilize metastable θ' precipitates (Al2Cu) for lengthy 350C exposures. Ultimately, Mn provides enough θ' stability to allow for slower diffusing Zr to segregate to θ' interfaces and form θ'/L12 (Al3Zr) co-precipitates. Rapid cooling during additive manufacturing allows for 10x’s more matrix Zr than cast-Al, which increases the Zr segregation rate and faster L12 precipitation on θ'. It was also found that planar L12 precipitates remain after the metastable θ' dissolves, as confirmed by atom probe tomography and scanning transmission electron microscopy experiments. This work introduces an alloy design strategy that uses metastable precipitates to quickly nucleate and grow co-precipitates with a desired geometry. These ideas can be applied to engineer new alloys that take advantage of supersaturated matrix solute contents enabled by rapid cooling during additive manufacturing. Microscopy was conducted at ORNL’s CNMS, which is a U.S. DOE Office of Science user facility.
10:50 AM
Additive Manufacturing of Highly-reinforced Metal Matrix Composites: Ethan Parsons1; 1MIT Lincoln Laboratory
The stiffness, strength, and thermal stability of particle-reinforced metal matrix composites (MMCs) are attractive for high-performance defense and space applications, but fabrication of MMC components with conventional methods is difficult, costly, and typically limited to components with simple geometry. Additively manufacturing particulate MMCs with laser powder bed fusion (LPBF) would be an ideal method, but the laser consolidation of these materials has been largely unsuccessful in matching the properties of conventionally-produced MMCs. Here, by mechanically alloying AlSi10Mg powder and ceramic microparticles, we manufacture highly-reinforced aluminum composite powders with morphology optimized for AM process conditions. The ceramic content, chemistry, and particle size are varied. Using LPBF, we achieve dense consolidation of these powders at ceramic contents of up to 40% and demonstrate tensile properties matching the properties of composites made by conventional methods.
11:10 AM
New Feedstock Design for Additive Manufacturing Using a Commercial Alloy Powder Mixture: Daozheng Li1; Wei Xiong1; 1University of Pittsburgh
Additive manufacturing (AM) is a powerful tool for alloy design and prototyping. However, the rapid heating and cooling cycle readily introduces texture with large columnar grains causing anisotropic properties and large residual stress, which significantly limits the application of the AM process over the traditional manufacturing methods. Therefore, there is an urgent need of discovering new alloys suitable for AM to reduce anisotropy in microstructure and properties. Through the ICME modeling and high-throughput characterization, a mixture of Stainless Steel 316L and Inconel 718 was designed using the laser powder bed fusion. After homogenization at high temperature, experimental observation confirms the expected phenomenon of grain refinement, which was identified in the same alloy mixture prepared by the directed energy deposition. Such grain refinement due to the hybrid effect of entropy, residual stress, and Zener pinning particles indicates a pathway of using commercial powder mixture to design new alloys for AM.