Thermodynamics and Kinetics of Alloys: Session I
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 8:30 AM
March 20, 2023
Room: Sapphire M
Location: Hilton
Session Chair: Ji-Cheng Zhao, University of Maryland; Kil-Won Moon, National Institute of Standards and Technology; Yijia Gu, Missouri University of Science & Technology
8:30 AM Invited
Thermodynamic Assessments and Experimental Validation of Iron “Impurity” in Cast Aluminum Alloys
: Alan Luo1; Siva Balasubramani1; Michael Moodispaw1; Jianyue Zhang1; Gabriel Garcia1; 1The Ohio State University
Iron (Fe) has long been treated as a major “impurity” element in cast aluminum alloys, due to its often detrimental effect on the mechanical properties of castings with high Fe contents. Fe can form numerous intermetallic phases in aluminum alloys depending on other alloying elements and cooling rates during solidification. The size, morphology, and volume fraction of these Fe-containing intermetallics have a pronounced effect on the mechanical properties of aluminum castings. This talk presents thermodynamic assessments and experimental investigation of various microalloying elements in neutralizing/reducing the detrimental effect of Fe-containing intermetallics in cast aluminum alloys. This research provides a scientific foundation for increasing secondary alloy usage and scrap recycling in aluminum casting industry.
8:50 AM Invited
First-principles Based Calculation of Thermodynamic and Kinetic Properties in Non-Dilute Mg Alloys Using CASM: Brian Puchala1; Anton Van der Ven2; 1University of Michigan; 2University of California, Santa Barbara
The open source software package CASM has been developed to take advantage of symmetry information to enable the study of thermodynamic and kinetic properties of multi-component alloys, including treatment of strain, vibrational, and magnetic effects. The CASM Alloy Manager helps researchers identify unique parent crystal structures in an alloy system, and manage individual CASM projects in which cluster expansion effective Hamiltonians are constructed, parameterized, and used in (kinetic) Monte Carlo calculations. To study kinetics, CASM includes features for enumerating possible diffusion events and local environments in order to automate first-principles based parameterization of local cluster expansions for diffusion barriers. In this talk we will describe using CASM to construct first-principles based free energy descriptions and calculate kinetic coefficients for diffusion in non-dilute Mg alloys, in order to link to higher length-scale models, such as the phase field method, used to study microstructural evolution.
9:10 AM
A First-principles Analysis of the Phase Stability of B2/BCC High Entropy Alloys: Julian Brodie1; Maryam Ghazisaeidi1; 1Ohio State University
BCC Refractory High Entropy Alloys (RHEAs) are interesting for their high yield strength and potential to replace Ni-based super alloys in high temperature applications. However, to date, there is still a lack of a fundamental understanding behind their mechanical properties. Furthermore, the fact these alloys tend to have multiple phases and components makes determining their mechanical properties more challenging. Thus, a study of the phases in these alloys is crucial for their future development. We use Density Functional Theory (DFT) to study the phase stability of the phases of a AlNbTaTiVZr BCC/B2 alloy. We compare the stability of competing phases as a function of pressure and temperature. We also investigate the role of constitutional point defects for the possibility stabilizing the phases.
9:30 AM Cancelled
Twin Nucleation from Stacking Fault Networks in Magnesium: Kehang Yu1; Xin Wang1; Subhash Mahajan2; Irene Beyerlein3; Penghui Cao1; Timothy Rupert1; Julie Schoenung1; Enrique Lavernia1; 1University of California, Irvine; 2University of California, Davis; 3University of California, Santa Barbara
Deformation twinning, an important plastic deformation mode, critically influences the strength and ductility of Mg. As such, a fundamental understanding of twin nucleation will provide us with important insight into the conditions that favor the onset of this deformation mode. To reveal the twin nucleation mechanism, we construct a dislocation network without making assumptions about the types and relative densities of dislocations present. The generated dislocation network features a high density of I1 stacking faults as well as disconnections between them. Deformation modeling reveals that this structure enables an unusual twin nucleation event. By probing twin nucleation and early-stage growth inside of this system, we propose a geometry-based twin variant selection rule and a pure-shuffle twin nucleation mechanism underpinning twinning in Mg.
9:50 AM
On the Effect of Different Elements on the Phase Stability of Bulk γ Alloys, Which Compositions Were Derived from Co-base Superalloys: Maik Rajkowski1; Mike Schneider1; Aleksander Kostka1; Christoph Somsen1; Guillaume Laplanche1; 1Ruhr-Universität Bochum
Here, we investigate how small chemical variations influence the phase stability of initially single-phase γ alloys. The γ-phase composition of a Co-base superalloy (ERBOCo-1) was determined by atom probe tomography, from which nine alloys were derived. These alloys contain mainly Co, followed by Ni, Cr, and W (major elements) with low quantities of other elements. In the first four alloys, the concentration of one of the major elements was reduced by ~5 at.% and compensated by increases in the concentrations of the other major elements while the contents of the minor elements were kept constant. In the other alloys, the compositions were simplified to quaternary CrCoNiW alloys such that the ratios between major elements remained the same. The alloys were cast, homogenized, cold-worked, and annealed for up to 1500 h followed by microstructural and chemical investigations including X-ray diffraction, scanning and transmission electron microscopies, and energy dispersive X-ray spectroscopy.
10:10 AM Break
10:30 AM Invited
Interfacial and Volumetric Melting Regimes of Sn Nanoparticles: Lucas Robinson1; John Blendell1; Carol Handwerker1; Edwin Garcia1; 1Purdue University
A thermodynamically consistent phase field formulation was developed to describe what has been historically known as the premelted surface layer in Sn nanoparticles. The derived formulation enables to identify interfacial phases, and the identification of four regimes of behavior: a) the classic premelting regime, in which the surface of the particle forms a liquid shell at temperatures below melting with clear delineation between the solid core and the premelted surficial liquid shell, as traditionally expected; b) the transition regime, in which the volumetric chemical potential and interfacial forces balance each other out; c) the disordered volume phase regime, in which a disordered interphase dominates the thermodynamic equilibrium of the system resulting in a partially crystalline core, and d) the mesoscale regime, in which the nanoparticles are no longer considered crystalline and experience an associated decrease in latent heat.
10:50 AM
Evaluation and Assessment of Interdiffusion Coefficients and Atomic Mobility in FCC Al-Cu-V: Yang Yang1; David Christianson1; Michele Manuel1; 1University of Florida
Solute additions of Si and Cu into industrial aluminum alloys are widely used to increase castability and ambient strengthening properties. The studies of adding rare earth elements into aluminum alloys are getting much more attention in recent decades since they have shown to improve the high-temperature performance. The optimization of the heat treatment on these alloys is critical to maximizing both the alloy’s ambient and high-temperature properties. However, currently there are not reliable kinetic descriptions of this system. Therefore, this study developed a kinetic mobility database to describe the FCC Al-Cu-V system using the experimental diffusion couple approach. The concentration profiles of Cu and V were measured using electron probe microanalysis (EPMA). The forward-simulation analysis (FSA) was employed to extract the interdiffusion coefficients. The experimentally determined diffusivities were then used to assess the mobility parameters utilizing the DICTRA Thermo-Calc Software package. The accuracy of the assessed parameters were then experimentally validated.
11:10 AM
Low Temperature Phase Equilibria Investigation and Phase Identification in the Cu-In-Sn System: Fu-Ling Chang1; Han-Tang Hung1; I-Chieh Fang1; Yu-Hsin Lin1; C.Robert Kao1; 1National Taiwan University
Nowadays, many applications require low soldering temperature process to avoid chip warpage and energy wasting during soldering. In-48Sn eutectic alloy was considered as a promising material to use at low temperature bonding, which with low melting temperature, excellent mechanical properties, high thermal conductivity and long fatigue life. In most cases, the application of this alloy is typically below 150°C, however, there is almost no information about the Cu-In-Sn phase diagram at this temperature region. In addition, there is no consensus on whether the intermetallic compound that appears at low temperature is Cu (In, Sn)2 or Cu2In3Sn. In this work, the Cu-In-Sn experimental phase diagram at 100, 80, 60°C and room temperature were studied, and the thermodynamic parameters for describing Cu-In-Sn phase equilibria were optimized, the agreement between the calculated and experimental results was also obtained.
11:30 AM
Experimental Investigation and Thermodynamic Assessment of the Cr-Si Binary System: Kazushige Ioroi1; Yuki Aono1; Xiao Xu1; Toshihiro Omori1; Ryosuke Kainuma1; 1Tohoku University
Cr-Si alloys are promising as high-temperature materials due to their high specific strength and oxidation resistance at high temperatures. The accurate phase diagram can guide the alloy design and heat treatment to enhance the mechanical properties of the Cr-Si alloys. However, reports on the phase equilibria, particularly in the Cr-rich portion, are limited because of the high melting point of Cr. In this study, phase equilibria in the Cr-Si binary system were evaluated experimentally and thermodynamically. Transformation temperatures and the solubility ranges of each phase were determined by thermal and composition analyses. The single-phase region of the Cr3Si phase was found to tend to incline toward the Cr-rich side with increasing temperature. On the other hand, the Cr5Si3 phase has a solubility range, extending toward the Si-rich side. Thermodynamic assessment was conducted by the CALPHAD method based on the experimentally determined phase diagram.
11:50 AM
Thermodynamic Assessment of the V-Ti-B System: Mustafa Yazlak1; Hans-Jürgen Christ1; Weiguang Yang2; Georg Hasemann3; Manja Krüger3; Bronislava Gorr4; 1Universität Siegen; 2Forschungszentrum Jülich; 3Otto-von-Guericke Universität Magdeburg; 4Karlsruher Institut für Technologie
Thermodynamic modelling is an effective approach to accelerate the development of novel materials such as V-based alloys. In the present work, the results of the thermodynamic modelling of the ternary system V-Ti-B using the “CALculation of PHAse Diagrams” (CALPHAD) method are presented. In order to validate calculated results, eleven different alloys in the compositional range of 10 to 40 at. % B and Ti were analysed aiming at identifying the appearing phases and their crystal structures. A set of thermodynamic parameters is proposed for the isothermal phase diagram at 1400°C which exhibits a very high agreement with experimental observations. Differential thermal analysis of selected alloys was applied to investigate the occurring phase transformation during heating/cooling. In our further work, Si will be added to the present thermodynamic database V-Ti-B envisaging the development of the quaternary dataset V-Ti-Si-B and their alloys.