Materials Design and Processing Optimization for Advanced Manufacturing: From Fundamentals to Application: Materials Design and Processing Optimization: Session VI
Sponsored by: TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Wei Xiong, University of Pittsburgh; Dana Frankel, Apple Inc; Gregory Olson, Massachusetts Institute of Technology
Wednesday 2:00 PM
March 2, 2022
Room: 253B
Location: Anaheim Convention Center
Session Chair: Yan Li, Dartmouth College; Victoria Miller, University of Florida
2:00 PM Invited
Alloy Design/Modification, Powder Feedstock Atomization and Process Optimization Modeling for Additive Manufacturing by Laser Powder Bed Fusion: Yongho Sohn1; Jeongmin Woo1; Abhishek Mehta1; Kevin Graydon1; Thinh Huynh1; Nathalia Diaz1; Asif Mahmud1; 1University of Central Florida
Laser powder bed fusion (LPBF) of metallic alloys is a transformative additive manufacturing technology for production of engineering components with nearly unlimited geometrical complexity and customization. This technology also brings an opportunity to develop new and modified alloys that take advantage of thermo-kinetic environment of LPBF, which warrants fundamental understanding of phase transformations and microstructural development. CALPHAD-based strategies in alloy design/modification coupled with experimental facility that includes gas atomization, laser powder bed fusion and a suite of microstructural and mechanical characterization are introduced, followed by selected results from Mg- Al-, Ti-, Fe-, Ni-, and multi-principal element alloys. Detailed observations on keyhole porosity, lack-of-fusion flaws, solidification microstructure and cracking are documented with respect to the alloy composition, solidification paths, and LPBF parameters. Computation investigations using generic algorithm and machine learning to establish process optimization for a wide range of metallic alloys based on their thermophysical properties are presented and discussed.
2:25 PM
Microstructure Prediction of Additively Manufactured 316L Using Heat Transfer, Thermodynamic, and Solidification Models: Charles Smith1; Olivia Denonno1; Matthew Schreiber1; Anthony Petrella1; Amy Clarke1; Zhenzhen Yu1; Jonah Klemm-Toole1; 1Colorado School of Mines
Microstructure development in fusion-based additive manufacturing (AM) starts with solidification. The vastly different microstructures observed across various AM processes of a given alloy have their origins in the thermal gradients (G) and interface velocities (V) that occur during solidification. In this presentation, we show how heat transfer, thermodynamic, and solidification models can be used to make predictions of the microstructure of 316L produced by laser powder bed fusion, laser wire directed energy deposition, and arc wire directed energy deposition. Methods to calibrate these models with characterization will be discussed. Applications of these experimentally validated models to predict microstructures irrespective of AM process will be explored.
2:45 PM
A New CALPHAD-based Approach to Develop Chromium and Nickel Equivalencies for Austenitic Stainless Steels: Benjamin Sutton1; Nathan Daubenmier1; Antonio Ramirez1; 1Ohio State University
The solidification cracking susceptibility of stainless steels is intimately related to whether austenite or ferrite form as the primary phase during solidification. Since the primary solidification mode of austenitic stainless steels is highly dependent on chemical composition, concerted efforts have been made to relate empirically-derived chemical equivalency relationships to primary phase selection. In this work, high-throughput computational thermodynamic simulations have been used to generate the requisite data to develop chemical equivalency relationships. Composition-dependent metrics related to solidification behavior were defined and served as the response variables to construct statistical models for two simulation types. The CALPHAD-based results were compared with legacy solidification mode data for austenitic stainless steel weld metals. Results indicate that stable/metastable liquidus temperature simulations provide a promising avenue to create chemical equivalency relationships. This approach can be tailored to scenarios where existing relationships do not adequately describe the composition space and/or dendrite growth velocities of interest.
3:05 PM
Microstructural Evolution of Compositionally Graded Proton Irradiated 316 Stainless Steel as a High Throughput Alloy: Laura Hawkins1; Jingfan Yang2; Xiaoyuan Lou2; Miao Song3; Yongfeng Zhang4; Daniel Schwen1; Lin Shao5; Lingfeng He1; 1Idaho National Laboratory; 2Auburn University; 3University of Michigan; 4University of Wisconsin - Madison; 5Texas A&M University
Development of high throughput materials characterization is an important capability for reducing the cost in classification of Generation IV candidate materials. A method for using laser engineering net shaping (LENS) to manufacture a compositionally graded 316L bar is reported. This study demonstrates high throughput capability by utilization of transmission electron microscopy (TEM) to characterize the effect of Hf as an oversized solute on irradiation response. Two types of additively manufactured samples were prepared: the as-built as a base material and the heat-treated material with a grain structure representative of traditionally forged 316L. Voids, dislocations and grain boundary segregation were characterized and the effect of precipitates on radiation damage was studied. The radiation hardening, measured from nanoindentation, was compared to the dispersed-barrier hardening model calculated from TEM results. The study demonstrated the feasibility of using compositionally graded steels as high throughput experimentation.
3:25 PM Break
3:40 PM
Material Interdiffusion and Necking between Dissimilar Nanoporous Metal Interfaces: Natalya Kublik1; Stanislau Niauzorau1; Sridhar Niverty2; Nikhilesh Chawla2; Bruno Azeredo1; 1Arizona State University; 2Purdue University
Nanoscale metal welding is a growing research area metal additive manufacturing at the micro and nanoscale as it yields metal sinterability at reduced temperatures. This paper examines the morphology evolution during sintering of nanoporous Cu powders dispersed over nanoporous Au thin films as a model system to understand atomic interdiffusion and necking across their interface at temperatures as low as 44% of their eutectic point. Both powders and thin-films are synthesized by chemical dealloying yielding ligaments that are 46 and 64 nm, respectively and sintered in a H2/Ar atmosphere at 400 °C and its cross-section are taken through their neck zone via focused ion beam milling to examine atomic concentration profiles via energy dispersive X-ray spectroscopy. Large diffusion penetration depths (i.e. 0.8 μm) across the interface are evidenced as well as evidence of neck formation between ligaments bridged across their original contact interface.
4:00 PM
A Numerical and Experimental Study of Simultaneous Topology/Orientation Optimization via SOMP and Principal Stress Directions: Bailey Brown1; Brett Compton2; Natasha Vermaak1; Nadim Hmeidat2; Jackson Wilt2; Xiu Jia1; 1Lehigh University; 2University of Tennessee, Knoxville
This research presents an analysis of simultaneous optimization of topology and material orientation based on a principal stress method within the Solid Orthotropic Material with Penalization (SOMP) framework. Numerical case studies were completed to assess the benefits of including orientation in the design process for minimum compliance structures comprised of anisotropic composite materials. Comparisons were made between topologies designed with orthotropic material properties and cases assuming isotropic material properties (using Solid Isotropic Material with Penalization – SIMP). Direct-Ink Writing (DIW) additive manufacturing was used to 3D-print the topologies (using a concentric slicing algorithm to approximate the prescribed orientation) which were tested in bending to validate numerical results. Results indicate that a concentric slicing algorithm closely approximates ideal orientation in optimized topologies and that no performance benefit is obtained from topologies that incorporate orientation into the optimization scheme over topologies optimized for isotropic materials, provided a concentric slicing algorithm is used.
4:20 PM
NOW ON-DEMAND ONLY - Designing Photopolymer Inks from Low Viscosity Newtonian Resins: Andrew Weems1; 1Ohio University-Main Campus
Polymeric photosets for 3D printing processes are one of the largest growing material classes globally, but the limited material library and functionality are consistent problems that limit expansion into industrial applications. Here, we leverage ring opening polymerization to produce low viscosity Newtonian photopolymer resins suitable for digital light processing (DLP) 3D printing. Through the use of compositing and simple organic modifications of the polymers, rheological and other physical properties of the photosets may be tuned towards transferring the resins into shear thinning inks for direct ink writing 3D printing. The balance of rheological properties with reactivity is also discussed, highlighting how the balance of properties may be leveraged for different impacts on layer integration, solidification, and part resolution. Ultimately, this design process may be further leveraged to enhance or install different functionalities including conductivity, photoresponsiveness, shape memory, and even degradability.
4:40 PM
Shear Assisted Processing and Extrusion (ShAPETM) for Manufacturing of Copper-graphene Composites for Ultra-high Electrical Conductivity: Emphasis on Microstructural Evolution: Bharat Gwalani1; Xiao Li1; Woongjo Choi1; Aditya Nittala1; Julian Escobar1; Joshua Silverstein1; William Frazier1; Keerti Kappagantula1; 1Pacific Northwest National Laboratory
Copper-graphene composites demonstrate electrical performance superior to commercial copper conductors. But bulk processing for industrial applications has been a big challenge. Recent research in friction-extruded copper-graphene composites via the Shear Assisted Processing and Extrusion (ShAPETM) shows an enhanced conductivity of ~105% IACS with very low graphene concentrations in bulk wires. However, the mechanisms for enhanced conductivity are not clearly understood. In this talk, we will present the results of a detailed investigation, using electron backscatter diffraction-based orientation microscopy, transmission electron microscopy, and atom probe tomography, of processed and semi-processed wire, used to elucidate material consolidation and microstructural changes during processing. The dispersion of graphene (graphitic domains) in the copper matrix and favorable textural alignment of copper grain are proposed to be responsible for enhanced room temperature conductivities. This understanding of process-structure-property relationships in copper composites can pave the way to further performance improvements in the next-generation energy-efficient conductor materials.