Thermodynamics and Kinetics of Alloys: Session II
Sponsored by: TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Ji-Cheng Zhao, University of Maryland; Wei Xiong, University of Pittsburgh; Chuan Zhang, CompuTherm LLC; Shuanglin Chen, CompuTherm LLC
Monday 2:00 PM
March 20, 2023
Room: Sapphire M
Location: Hilton
Session Chair: Bi-Cheng Zhou, University of Virginia; Shalini Roy Koneru, The Ohio State University
2:00 PM Invited
Effect of N and/or B Additions on the Precipitation Kinetics in Isothermally Aged and Creep Ruptured 347H Stainless Steels: Qing-Qiang Ren1; Yukinori Yamamoto1; Michael Brady1; Jonathan Poplawsky1; Martin Detrois2; Paul Jablonski2; Jeffrey Hawk2; 1Oak Ridge National Laboratory; 2National Energy Technology Laboratory
Precipitation kinetics of three 347H stainless steels (UNS-S34709) with changes in the N (22-168 wppm) and B (<5 and 11 wppm) contents were experimentally evaluated through microstructure characterization by electron microscopy and atom probe tomography after isothermal aging at 750 °C and creep-rupture testing at 600-750 °C. The obtained precipitation behavior was used to support modeling-and-simulation activities for material life assessment under the on-going eXtremeMAT (XMAT) program funded by the US-Department of Energy, Office of Fossil Energy and Carbon Management. Strengthening metastable M23C6 carbides formed in the early stage of isothermal aging are replaced by sigma phases after prolonged exposure. B additions significantly improved the M23C6 stability relative to the sigma phase, while N additions did not. Creep deformation, on the other hand, accelerated the transition from M23C6 to sigma. The transition mechanism will be discussed with the analyzed composition and precipitate stability.
2:20 PM
Accelerated CALPHAD-based Design of a 7xxx High Strength Aluminum Plate Alloy: Maria-Ioanna Tzini1; Gregory Olson1; 1Massachusetts Institute of Technology
High-strength aluminum plate alloys are widely used in the aerospace and defense industry due to their high specific strength and good workability. In comparison to the trial-and-error strategies, the design of these alloys can be significantly accelerated by using computational alloy design approaches. In the present study, CALPHAD-based ICME tools are employed for the design of an Al-Zn-Mg-Cu-Zr high-strength plate alloy, compatible with ingot metallurgy and wrought processing to a 10 cm thickness plate. Aiming in maximizing the yield strength and improving the elongation, toughness, and quench sensitivity of this alloy, specific alloy and process design criteria are applied. An Orowan precipitation strengthening model is developed to describe the hardening behavior upon aging, while the distribution of grain refining phases is predicted via thermodynamic and kinetic calculations. A multi-objective optimization problem is formulated and then the optimum composition and processing parameters are determined for the integrated system via genetic programming.
2:40 PM
Al-Ce Alloy Development Using Computational Thermodynamics: Emily Moore1; Hunter Henderson1; David Weiss2; Scott McCall1; Orlando Rios3; Aurélien Perron1; 1Lawrence Livermore National Laboratory; 2Eck Industries Inc.; 3University of Tennessee, Knoxville
Development of Al-Ce alloys is investigated to improve the mining economics of rare-earth elements (REE) used in clean energy technologies. Thermochemical models using the CALPHAD (CALculation of PHAse Diagrams) method aid in alloy design by predicting the phase-behavior of multi-component systems to achieve the desired chemical makeup of an alloy. We present a thermodynamic database that addresses multi-element alloys within the Al-Ce-Cu-Fe-La-Mg-Mn-Ni-Si-Zn-Zr system and investigate alloy compositions considered for fast deployment of high-volume applications within the automotive industry. 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.
3:00 PM
CALPHAD and Data-driven Approach for Phase Prediction Model in Refractory High-entropy Alloys: Jiwon Park1; Chang-Seok Oh1; 1Korea Institute of Materials Science
In this work, a data-driven approach is proposed for the phase prediction models and feature selection strategies in refractory high-entropy alloys (RHEA) based on the data collected from the literature, CALPHAD computations, and data analyses. Themodynamic properties such as liquidus and solidus temperatures, and the enthalpy of mixing were added to extend relevant features. As the dataset consists of many features compared to the number of composition sets, dimensionality reduction is essential to improve the model efficiency. Several dimensionality reduction methods including PCA and GA in feature selection are compared, and the machine learning models are explained by Sharpley values in the phase classification models when the phases are categorized in 4 classes; single BCC, phase-separated BCCs, BCC, FCC and/or HCP, and mixture of BCC and intermetallic.
3:20 PM Break
3:40 PM Invited
Tunable Heterogeneous Microstructures in a High Throughput Architecture: Markus Short1; 1Karlsruhe Institute for Technology
A new method applied to the sensor proposed by Zhang et al. in 2018 will be presented that combines the benefits of this design with the fast heating possible with nanocalorimetry. By applying a PID regulated pulse instead of constant wattage, we unlock an accessible method to sense quick microstructural changes that would be invisible to heat capacity based measurements. In this study, multilayer Ni/Al thin films were linearly heated at 25, 50, 100, and 200 K/s to over 700°C, showing two distinct peaks in resistance change. Through SAD, STEM, and EDX analysis on cross sections taken ex-situ from samples quenched before and after these peaks of interest, we find strong evidence that peak 1 corresponds to Ni diffusing through Al grain boundaries forming intermetallic phases that inhibit the highly conductive Al pathway. This presents the potential to design and calibrate novel heterogeneous structures in a high throughput manner.
4:00 PM Invited
Impact of Magnetic Excitation and Transition on Atomic Diffusion in Fe Alloys: Chu-Chun Fu1; Anton Schneider1; Kangming Li1; 1Université Paris-Saclay, CEA, Service de Recherches de Métallurgie Physique
Several thermodynamic and kinetic properties of Fe alloys are strongly affected by magnetism. With increrasing temperatures, magnetic excitations and lattice vibrations emerge and interact with chemical effects.. So far, a quantitative modelling of these coupled effects is still challenging. We propose an efficient modelling approach to predict atomic-diffusion properties versus temperature and composition. It consists in coupled spin-atomic Monte Carlo simulations using magnetic effective interaction models parameterized from first-principles results. We apply the method to predict equilibrium vacancy concentration and tracer diffusion coefficients in dilute and concentrated Fe alloys. We focus particularly on the effects of magnetic excitation and transition. The obtained results are consistent with available experimental data.This approach is also promising for the study of more complex kinetic processes such as phase ordering and precipitation.
4:20 PM
Effect of Ti on the Diffusional Growth of A15 Nb3Sn: Sang-Ho Oh1; Yang-Jin Jeong2; Sin-Hye Na2; Iksang Shin2; Jiman Kim2; Byeong-Joo Lee1; 1Pohang University of Science and Technology; 2Kiswire Advanced Technology Ltd.
A15 Nb3Sn is one of the mostly used materials for superconducting wire applications. Manufacturing technologies of Nb3Sn wire products are based on the diffusion of Sn and the diffusional growth of Nb3Sn compound during a heat treatment. Alloying elements such as Ti are reported to dramatically promote the growth rate of the Nb3Sn layer, but the detailed mechanism of such effect is not fully understood yet. To optimize the alloying strategy for the Nb3Sn products, details of alloying effects should be investigated based on a fundamental understanding of diffusion phenomena. We employed atomistic simulations based on a 2NN MEAM interatomic potential to investigate the detailed diffusion mechanism in the Nb3Sn compound and clarified the major diffusion path in Nb3Sn. Based on this, we investigated the atomic behavior of Ti in Nb3Sn compound and clarified details of alloying effects on the diffusional growth of the Nb3Sn layer.
4:40 PM
The Selection of Solidification Pathway in Rapid Solidification Processes: Nima Najafizadeh1; Yijia Gu1; 1Missouri University of Science and Technology
Rapid solidification processing of alloys enables the formation of exotic non-equilibrium microstructures. However, the interrelationship between the processing parameters and the resulting microstructure is yet to be fully understood. In melt spinning and additive manufacturing of rapidly solidified alloys, opposite microstructure development sequences were observed. A fine-to-coarse microstructural transition is typically observed in melt-spun ribbon, while a coarse-to-fine transition pattern is shown in AM melt pools. In this work, the microstructural evolutions during these two processes are investigated using phase-field modeling. It is found that the onset of nucleation determines the selection of solidification pathway and consequently the development of those different microstructures. The switching of control mechanisms of the solid-liquid interface, which happens in both processes but in opposite directions, is found to cause the velocity jump and disrupt the microstructure development.
5:00 PM
Study on Densification Kinetics of the Binder Jetted Fine 316L SS Powder: Mohammad Jamalkhani1; Maciej Dorula1; Elijah Roberts1; Julia Deguia1; Amir Mostafaei1; 1Illinois Institute of Technology
With the growth of binder jetting, an understanding of microstructural evolution and densification within large parts during sintering is necessary. Gas atomized 316L SS powder is 3D-printed and vacuum-sintered to extend existing knowledge of sintered binder jetted fine powder. Sintering temperature and holding time affect linear shrinkage, densification and pore evolution. Stereological measurements was applied on scanning electron micrographs. A database of grain and pore intercept length, pore separation, surface area per unit volume and number of pore sections per unit area will be developed to better understand sintering kinetics, microstructural evolution and, finally, sintering mechanisms of binder jetted 316L SS. Also, densification behavior and deformation will be studied using an innovative in-situ optical imaging system in which anisotropy shrinkage in binder jetted alloys are visualized during sintering. These in-situ observations can be used to validate simulations and numerical model during sintering of binder jetted parts.