Materials Processing Fundamentals: On-Demand Oral Presentations
Sponsored by: TMS Extraction and Processing Division, TMS Materials Processing and Manufacturing Division, TMS: Process Technology and Modeling Committee
Program Organizers: Samuel Wagstaff, Oculatus Consulting; Alexandra Anderson, Gopher Resource; Jonghyun Lee, Iowa State University; Adrian Sabau, Oak Ridge National Laboratory; Fiseha Tesfaye, Metso Outotec Finland Oy

Monday 8:00 AM
March 14, 2022
Room: Materials Processing
Location: On-Demand Room

Anomalous Temperature Effect on Diffusion-controlled Solidification Time during Diffusion Brazing: Oluwadara Afolabi1; Olanrewaju Ojo1; 1University of Manitoba
    The anomalous increase in diffusional solidification time with increase in bonding temperature during diffusion brazing has been widely observed experimentally in the literature; however, no adequate explanation has been provided. In this work, systematic theoretical modelling is used to study the fundamental mechanisms responsible for this anomaly. It is found that inadequate increase in diffusional solidification rate to overcome the accompanying increase in volume of liquid with increase in temperature would result in the anomaly. Results also show that reduction of diffusional solidification rate with increase in temperature, which can occur despite an attendant increase in diffusivity, would likewise cause the anomaly. Moreover, the study reveals that it is possible for concentration-averaged diffusion coefficient to reduce with increase in temperature when diffusivity is concentration-dependent, and this can equally result in the anomaly. The identified mechanisms which offer new understanding about the phenomenon are validated by experimental observations in the literature.

Comprehensive Recovery of Pressure Acid Leaching Residue of Zinc Sulfide Concentrate: Guiqing Liu1; Bangsheng Zhang2; Zhonglin Dong3; Fan Zhang2; Fang Wang2; Tao Jiang3; Bin Xu3; 1Northeastern University; 2Jiangsu BGRIMM Metal Recycling Science & Technology Co. Ltd; 3Central South University
    Pressure acid leaching residue of zinc sulfide concentrate contains abundant elemental sulfur that has excellent natural hydrophobicity, and thus it is considered an important secondary resource for recovering elemental sulfur with froth flotation technique. However, the separation of elemental sulfur from sulfide minerals in the residue is difficult mainly because of their similar hydrophobicity. In this research, we proposed an effective flotation process for selective recovery of elemental sulfur from a pressure acid leaching residue of zinc sulfide concentrate. After one-time blank rougher, two-time agent-added roughers and two-time cleaners separately using O-isopropyl-N-ethyl thionocarbamate as the collector and combined agent Na2SO3+ZnSO4+Na2S as the inhibitor, 99.9% of the elemental sulfur was recovered and the purity of concentrate product achieved 83.5%. Most of the lead, zinc and silver went into the tailing that can be used as the raw material of pyrometallurgical lead smelting for recovering these valuable metals.

Time Variation of Concentration-dependent Interdiffusion Coefficient: Osamudiamen Olaye1; Olanrewaju Ojo1; 1University of Manitoba
    The long-held assumption that the concentration dependence of interdiffusion coefficient (D(C)) is an isothermal constant that does not change with time is investigated theoretically and experimentally. Theoretically, D(C) is evaluated from concentration profiles obtained numerically at different times under the influence of diffusion-induced stress. Experimentally, a new numerical model and the forward simulation technique are used to extract D(C) from several experimental profiles at several diffusion times. Although not commonly acknowledged, the results of the theoretical and experimental investigations show that even in binary systems, under isothermal conditions, D(C) can significantly change with time. Furthermore, trivializing this concept can lead to a notable misinterpretation of experimental data, including a consequential misidentification of the mechanism of microstructural changes by phase transformation reactions.

Study of γ'-Fe4N Material Annealing through Molecular Dynamics Modeling: Jianxin Zhu1; Guannan Guo1; Jian-Ping Wang1; 1University of Minnesota
     γ’-Fe4N thin film is considered as a potential precursor to synthesize α″-Fe16N2, which is a promising high saturation magnetization permanent magnetic material that could be attained from the decomposition of the high nitrogen content iron nitride at appropriate temperature. High temperature thermal annealing process of γ’-Fe4N material is studied using Molecular Dynamics (MD) modeling method. With Modified-Embedded-Atom-Method (MEAM) interatomic potential of Fe-N and bond forming/breaking MD simulation, the number of Nitrogen bonds formed is found to be insignificant. Results suggests the formation of N2 bonds requires high temperature and existing of lattice imperfections, i.e. where neighboring N atoms can be much closer than 2nd nearest-neighbor (2NN) distance.

Potentiostatic Electrodeposition of Ti-Al Alloy with 40% Titanium from the Lewis Acidic 1-butyl-3-methylimidazolium Chloride-aluminum Chloride Ionic Liquid Electrolyte: Pravin Shinde1; Yuxiang Peng1; Ramana Reddy1; 1The University of Alabama
    Ti-Al alloys were electrodeposited from the Lewis acidic ionic liquid (IL) containing 1-butyl-3-methylimidazolium chloride (BMIC) and aluminum chloride (AlCl3). A constant potential electrodeposition was performed in a two-electrode configuration on copper cathode for 4 h at 383 K from BMIC-AlCl3 electrolytes with different AlCl3 mole fractions and deposition potentials. Titanium was served as anode and also the source of Ti ions. Ti-Al alloys deposited on Cu substrate at different synthesis conditions were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. A Ti0.4Al0.6 phase with 40-atom % Ti was obtained in the final deposit at optimized parameters and was confirmed by repeating electrodeposition experiments with identical synthesis conditions. The cathode weight gain and anode weight loss was measured to determine the Faradaic current efficiency and energy consumption values of Ti-Al electrodeposition process. More work is underway to further improve the percentage of Ti in the Ti-Al deposits.

Thermodynamic Properties of Sulfur in the CaO–AlO1.5–CeO1.5 Slag System at 1873 K: Masaya Higuchi1; Kazuki Morita1; 1The University of Tokyo
    Rare earth elements (REs) have a high affinity for oxygen and are effective as deoxidizers and desulfurizers. The addition of REs to Al-killed steel in the presence of CaO flux is expected to produce CaO-AlO1.5-REOX oxides. Ce was focused on as the main component of the mish metal and the phase equilibrium of the CaO-AlO1.5-CeO1.5 system at 1873 K and the deoxidation equilibrium was measured. In this study, to confirm the usefulness of Ce as a desulfurizer, Ce was added to the Fe-S alloy which was coexisting with CaO-AlO1.5-CeO1.5 slag. As the result, oxygen potential in the steel was considerably decreased by the strong reducing agent Ce, and the S concentration was found to be reduced to less than 10 ppm. In order to quantitatively evaluate the desulfurization effect of this slag, the sulfide capacity (CS2-) at 1873 K was measured.

Evaluation of Phase Relations for the Al-Cu-Mg-Si-Zn System around Eutectic Composition: Yusuke Kageyama1; Kazuki Morita1; 1The University of Tokyo
    While photovoltaic power generation has the advantage of emitting no CO2 during operation, it also has the problem that the amount of power generated is greatly affected by the weather, which sometimes leads to disconnection from the power grid. As a solution to this problem, latent heat storage(LHS) materials, which make thermal power plants easier to have flexible output adjustment capability, have gained much attention. Specifically, eutectic alloys are considered promising because of their homogeneous melting behavior. However, little choice is known about eutectic alloys used between 450-500 ℃, although heat storage systems require several LHS materials with different eutectic temperatures. To solve this problem, this research aims to find a new multi-component eutectic alloy by using SEM-EDS and TG-DTA analysis. Results showed the eutectic composition and temperature of Al-Cu-Mg-Si-Zn, and that it is one of the promising choices for LHS materials.

Prediction of Distribution of Composition of Inclusion in Continuous Casting Bloom of the Heavy Rail Steel Coupling Element Segregation, Heat Transfer and Kinetics: Yuexin Zhang1; Wei Chen2; Jujin Wang1; Yadong Wang1; Wen Yang1; Ying Ren1; Lifeng Zhang2; 1University of Science and Technology Beijing; 2Yanshan University
    Inclusions in heavy rail steels are mainly CaO-SiO2-Al2O3-MgO.A dynamic model had been used to predict the distribution of composition of inclusions in continuous casting bloom of the heavy rail steel. On this basis, the elemental segregation model was introduced to predict the distribution of inclusions in CC bloom. Samples from the inner arc to the outer arc of the bloom were selected as research objects. Element distribution results were calculated by the segregation model. Then, calculation of mold transient flow field, heat transfer and solidification, thermodynamic analysis and element diffusion were combined to predict the composition distribution of inclusions in the whole section of the bloom. Predicted results were basically consistent with actual results. The result not only verifies the correctness of the model, but also has a certain guiding significance to the actual steelmaking process.

Voltammetric Investigations of the Dissolution of Copper in Acidic Cupric Chloride Solutions Containing Additional Dissolved Cuprous Ions: Nadine Koerbler1; Eva Gerold1; Thomas Krivec1; Jolanta Klocek1; Helmut Antrekowitsch1; 1Montanuniversity of Leoben
    The impact of additional cuprous ions on the dissolution of pure copper in acidic cupric chloride solutions and the behavior of individual copper chloride complexes were investigated by detecting characteristic current potential curves using a rotating disk electrode setup. Due to the variation of different parameters like temperature, rotation speed and concentration of the reactive species the influence on the conversion rate can be interpreted. This work deals with the application of voltammetry in a three-electrode setup. In this system, a pure copper sample was installed as a working electrode and contacted with defined acidic solutions containing certain copper ions. Elevated temperatures and rotation speeds amplify the reactions between electrolyte and metal. Higher concentrations cause pronounced concentration gradients, which affect the diffusion of reactive ions. Further studies on the formation of copper chloride complexes should provide more information on optimized solutions.

Site Preference of Ti in 6H-SiC: A Combined Photoluminescence and Theoretical Calculation Study: Hui Chen1; Kazuki Morita1; 1University of Tokyo
    SiC is a promising material for high-voltage power devices due to its high electron mobility. The top seeded solution growth (TSSG) method is an efficient method to grow SiC from the Si–Ti solvent at low temperature, and therefore, Ti exists as a background impurity in the SiC crystals produced by TSSG. The Ti impurity affects the properties of SiC by forming deep levels inside the bandgap, and as thus, reducing the minority carrier lifetime. However, it is difficult to confirm the site preference of Ti in 6H-SiC, since the Ti acceptor level is inactive in 6H-SiC. In this work, a combined photoluminescence (PL) and theoretical calculation study was conducted to research the bonding state of Ti in 6H-SiC. The PL spectra for the Ti-doped 6H-SiC were measured at low temperature, and the corresponding theoretical calculation was performed to confirm the site preference of Ti in 6H-SiC.

Measurement of Thermodynamic Property of Mg in Molten Iron at 1823 K by Transpiration Method: Tomoya Nakamura1; Akiko Nakajima1; Kazuki Morita1; 1Graduate School of Engineering, The University of Tokyo
     Magnesium, which has high affinity for oxygen and sulfur, is useful for deoxidization and desulfurization in steelmaking processes. In order to optimize such processes, thermodynamic property of Mg in molten iron is indispensable. However, because of its high reactivity and high vapor pressure, there are few reliable thermodynamic data at steelmaking temperatures.In this study, molten iron was equilibrated at 1823 K in a controlled Mg chemical potential by transpiration method. Hydrogen added argon gas with a certain Mg partial pressure was flown onto molten iron, followed by chemical analyses of Mg and oxygen contents of iron. Then the standard Gibbs energy of dissolution reaction of Mg into molten iron was clarified also by eliminating the effect of oxygen using the first and second order interaction parameters between oxygen and Mg.