Advanced Real Time Imaging: Alloys, Ceramics, and Additive Manufacturing
Sponsored by: TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Alloy Phases Committee, TMS: Biomaterials Committee
Program Organizers: Jinichiro Nakano, US Department of Energy - National Engergy Technology Laboratory; David Alman, National Energy Technology Laboratory; Il Sohn, Yonsei University; Hiroyuki Shibata, Tohoku University; Antoine Allanore, Massachusetts Institute of Technology; Noritaka Saito, Kyushu University; Anna Nakano, US Department of Energy National Energy Technology Laboratory; Zuotai Zhang, Southern University of Science and Technology; Candan Tamerler, University of Kansas; Bryan Webler, Carnegie Mellon University; Wangzhong Mu, Kth Royal Institute of Technology; David Veysset, Stanford University; Pranjal Nautiyal, University of Pennsylvania

Tuesday 8:00 AM
March 1, 2022
Room: 206A
Location: Anaheim Convention Center

Session Chair: Wangzhong Mu, Kth Royal Institute of Technology

8:00 AM  
In-situ Observation of Phase Transformations in Co-based Dual Phase Entropic Alloys Using High Temperature Confocal Laser Scanning Microscopy: Wangzhong Mu1; Wei Wang2; Ziyong Hou3; Sohei Sukenaga4; Hiroyuki Shibata4; Henrik Larsson1; Huahai Mao1; 1KTH Royal Institute of Technology; 2Northeast Electric Power University; 3International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering & Shenyang National Laboratory for Materials Science, Chongqing University; 4Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
    Entropic alloys, an extended definition of high entropy alloys (HEAs) is a new family of alloy grades which has attracted the attention of the community progressively during the past decade. Co-based dual phase entropic alloys (DP-EAs) including fcc and hcp structure are designed very recently to overcome the strength-ductility trade-off, due to a combination of outstanding yield strength and good ductility. In this work, high temperature confocal laser scanning microscopy (HT-CLSM) is applied to observe the athermal martensitic transformation in Co-based DP-EAs. It is the first time to provide an in-situ real observation study to investigate the phase transformation in the entropic alloys using HT-CLSM. A correlation between martensite starting temperature and its fraction could be found, and the morphology and nucleation sites for martensite formation is discussed. This current methodology as well as the obtained knowledge could be applied for a comprehensive fundamental study for high entropy alloy design.

8:20 AM  
Assessing the Evolution of Pit Growth Kinetics during Atmospheric Corrosion Using In-situ X-ray Tomography: Philip Noell1; Eric Schindelholz2; Michael Melia1; Ian Campbell1; 1Sandia National Laboratories; 2The Ohio State University
    Within the field of corrosion, the relationship between environment and the kinetics of pit growth during atmospheric corrosion attack remain poorly understood. Using in-situ X-ray microtomography, we directly observed pit growth in Al materials and the relationship between growth kinetics and the evolving surface environment over months of exposure. While previous studies suggested that growth kinetics are roughly linear, the present study indicates that growth rates can vary significantly in some cases. This depends on the evolution of the droplet, e.g. droplet spreading, as well as the morphology of the pit. In-situ measurements also revealed that in the hours immediately before repassivation, growth stalled then accelerated. A corrosion-driven drying mechanism is hypothesized to change droplet chemistry and produce this behavior. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

8:40 AM  
In-situ X-ray Imaging of Melt Flow and Melt Pool Variation during Laser Metal Additive Manufacturing Process: Qilin Guo1; Cang Zhao2; Minglei Qu1; Lianghua Xiong3; Luis I. Escano1; S. Mohammad H. Hojjatzadeh1; Niranjan D. Parab2; Kamel Fezzaa2; Wes Evehart4; Tao Sun2; Lianyi Chen1; 1University Of Wisconsin Madison; 2Argonne National Laboratory; 3Missouri S&T; 4Department of Energy’s Kansas City National Security Campus Managed by Honeywell FM&T
    The size/shape of the melt pool and the flow behavior within a melt pool play a critical role in determining the microstructure in additively manufactured parts. However, it is challenging to experimentally characterize the physics within a metal melt pool due to its non-transparency to most of the optical-based imaging techniques. Here, with in-situ high-speed high-energy synchrotron X-ray imaging, we quantitatively characterized the melt pool and melt flow variation under different laser metal additive manufacturing conditions, and revealed the mechanisms underlying these variations. The results are critical for understanding the laser metal additive manufacturing process and beneficial for designing better processing parameters.

9:00 AM  
Two-color Pyrometry as a Defect Predictor in the Additive Manufacturing of 316L Stainless Steel: Mary Arnhart1; Andrew Polonsky1; Thomas Ivanoff1; John Mitchell1; Bradley Jared1; Daryl Dagel2; Jonathan Madison1; 1Sandia National Laboratories; 2Ball Aerospace & Technlogies Corporation
    Corroborating in-situ two-color pyrometry with post-build micro-computed tomography has previously been demonstrated to reasonably identify defects in additively manufactured 316L stainless steel. Overcoming resolution variance between imaging modalities and resolving non-uniform distortions in pyrometry data reveal a greater predictive ability for this in-situ technique than previously observed. This talk will also show how effective and reliable identification of anomalous melt pools can be leveraged toward informing real time processes to better mitigate the occurrence of defects in additive manufacturing builds by intercepting the events that result in pore formation before they occur. Additional recommendations for the practical integration of two-color pyrometry in additive manufacturing will also be provided.

9:20 AM Break

9:40 AM  
Visualizing the Path of Corroding Mg Alloys Using High Phase Contrast X-ray Computed Tomography: Chi Zhang1; Junsheng Wang1; Chen Liu2; Keli Liu1; Guangyuan Tian1; Xin Li1; 1Beijing Institute of Technology; 2Ningbo Branch of Chinese Academy of Ordnance Science
    Corrosion of Mg alloys is highly influence by the alloying additions. However, no direct observation of how secondary phases as a result of alloying would form localized battery cells. Here we advanced our understanding of the effects of secondary phase distribution on Mg alloy corrosion using laboratory X-ray computed tomography with phase contrast. It was found that the equivalent diameter and distances between secondary phases have large impact on the localized corrosion path, providing guidance for corrosion resistance alloy development.