Materials Processing Fundamentals: Poster Session
Sponsored by: TMS Extraction and Processing Division, TMS Materials Processing and Manufacturing Division, TMS: Process Technology and Modeling Committee
Program Organizers: Jonghyun Lee, Iowa State University; Samuel Wagstaff, Oculatus Consulting; Alexandra Anderson, Gopher Resource; Fiseha Tesfaye, Metso Metals Oy, Åbo Akademi University; Guillaume Lambotte, Boston Metal; Antoine Allanore, Massachusetts Institute of Technology
Wednesday 5:30 PM
March 17, 2021
Room: RM 42
Location: TMS2021 Virtual
Containerless Materials Processing for Materials Science on Earth and in Space: Jonghyun Lee1; Sai Katamreddy1; Yong Chan Cho2; Sooheyong Lee2; Geun Woo Lee2; 1Iowa State University; 2Korea Research Institute of Standards and Science
Electromagnetic and electrostatic levitation techniques have been utilized for the last few decades to process metastable and highly reactive materials. Main fields of application include thermophysical properties, solidification, and transport phenomena of molten metals, which are of critical importance to better understand and control manufacturing processes dealing with molten metals, such as casting, welding, and additive manufacturing. This paper addresses part of our international collaborative work with NASA, European Space Agency, German Aerospace Center, and Japanese Aerospace Exploration Agency to support containerless experiments aboard the International Space Station. Along with space experiments, our recent work using an electrostatic levitator to unveil the liquid structure of aqueous sodium sulfate solutions (the most damaging salt to civil structures) is also introduced.
Effect of Nitrogen on Weldability and the Microstructure in Laser Beam Welding of Duplex Stainless Steel: Yunxing Xia1; Kenshiro Amatsu1; Fumikazu Miyasaka1; Hiroaki Mori1; 1Osaka University
Due to unbalanced phases' contents in welds of duplex stainless steel, their mechanical properties, and corrosion resistance should be remarkably degraded from base metals' ones. It was reported that both the precipitation and growth of the austenite phase in the welds are affected by the nitrogen contents as well as thermal cycles of welding. Especially, in the case of laser beam welding (LBW), these effects might be drastically changed as compared with them in conventional welding methods. From the microstructure observation in the LB welds used Argon shielding gases varied with nitrogen contents of 0%, 10%, and 20%, austenite phases growth at grain boundaries were promoted by the increase in nitrogen contents in the shielding gases. Based on elements' distributions measured in the previous report by an EPMA analysis, nitrogen was powerfully concentrated in austenite in each case. In addition, the in-situ observation by the micro-focused X-ray transmission imaging system revealed that porosity in the LB welds was suppressed by the increase of nitrogen in Argon shielding gases. That is, these results suggested that under suitable thermal history conditions, the addition of nitrogen in Argon shielding gas for LBW might be effective to increase in austenite contents in welds of duplex stainless steels.
Thermodynamic Examination of Quaternary Compounds in the Ag–Fe–(Ge, Sn)–Se Systems by the Solid-state EMF Method: Mykola Moroz1; Fiseha Tesfaye; Pavlo Demchenko2; Myroslava Prokhorenko3; Bohdan Rudyk1; Lyudmyla Soliak1; Daniel Lindberg4; Oleksandr Reshetnyak2; Leena Hupa5; 1National University of Water and Environmental Engineering; 2Ivan Franko National University of Lviv; 3Lviv Polytechnic National University; 4Aalto University; 5Åbo Akademi University
The equilibrium phase space of the Ag–Fe–X–Se (X: Ge, Sn) systems in the parts Ag8XSe6–XSe–FeSe2–AgFeSe2–Ag8XSe6 consists of four quaternary-phase regions formed with the participation of low-temperature modifications of the Ag2FeGeSe4 and Ag2FeSnSe4 compounds. The kinetic barriers of the formation of equilibrium four-phase regions that are observed under conditions of vacuum ampoule synthesis below 600 K were overcome by synthesis of phases at the positive electrodes of electrochemical cells (ECCs): (−)C|Ag|SE|R(Ag+)|PE|C(+), where C is graphite, Ag is left (negative) electrode, SE is the solid-state electrolyte, PE is the right (positive) electrode, and R(Ag+) is the region of Ag+ diffusion into PE. Silver cations Ag+ that shifted from the left to the right electrode of ECCs acted as the seed centers of an equilibrium set of phases. Based on the temperature dependences of the EMF of the cells in the temperature range 430–485 K, the standard thermodynamic functions of the Ag2FeGeSe4 and Ag2FeSnSe4 compounds were calculated for the first time. The observed experimental results and thermodynamic calculations are in good agreement.