Computational Thermodynamics Byeong-Joo Lee Computational Materials Science & Engineering Lab. Pohang University of Science & Technology
Structure Evolution Process Condition Materials Property R&D in Materials Science and Engineering Structure Evolution Process Condition Materials Property Research Type I : experiments first, then thinking Research Type II: think first, then do experiments
Thermodynamic Modelling
Lattice Stability
Regular Solution vs. Quasi-Chemical Model
Thermodynamic Assessment – Cr-Ni Binary System LfccCr,Ni = 8030 – 12.8801·T + (33080 – 16.0362·T)(1-2XNi) LbccCr,Ni = 17170 – 11.8199·T + (34418 – 11.8577·T)(1-2XNi) LliqCr,Ni = 318 – 7.3318·T + (16941 – 6.3696·T)(1-2XNi) B.-J. Lee, 1992
Thermodynamic Assessment – Fe-Cr-Ni Ternary System B.-J. Lee 1993
Thermodynamic Parameters (Fe,Cr,Mo)(Va,B,C,N)
Thermodynamic Modeling – Gibbs Energy For a Phase with Formula Unit, (M1,M2,…,Mi,…)a(Va,C,N)c
Thermodynamic Modeling – Gibbs Energy For a Phase with Formula Unit, (M1,M2,…,Mi,…)a(Va,C,N)c
Thermodynamic Database for Steels – TCFe2000 → TCFe2 → TCFe3 Fe-Cr-Ni-Mo-Mn-Si-C-N +Nb-Ti-V-W-Al-Co-Cu-B-O-P-S 8C2 = 28 Binary Systems 8C3 = 56 Ternary Systems 19C2 = 171 Binary Systems 19C3 = 969 Ternary Systems
Solution Models - liquid and fcc Fe-C alloys
Solution Model - liquid and fcc Fe-C alloys fcc : (Fe)1(Va,C) 1 Liquid : (Fe,C) Ternary (Fe,Mn)a(Va,C) c
Applications of Computational Thermodynamics
Thermodynamic Calculation – Practical Steels
Thermodynamic Calculation – Application to Alloy Design Computational Thermodynamics의 적용 분야 Structural Materials (Steel, Solder, Al-, Ti-, Ni-, Mg-alloys), Semiconducting Materials, Ceramic Materials, Hydrogen Storage Materials, CVD process 등 열역학이 지배하는 모든 물질계
Thermodynamic Calculation – Application to Alloy/Process Design AB1: 0.1C-5MN-7Al AB2: 0.2C-4Mn-6.6Al AB3: 0.3C-3.5Mn-6Al AB4: 0.4C-3.5Mn-5.8Al AB5: 0.5C-3Mn-4.9Al AB6: 0.3C-4Mn-7.3Al-0.05Ti
Thermodynamics Assessment - Na-Al-H system
Assessment of thermodynamic properties in the Li-Al-H ternary system
Driving force of CVD Deposition ※ Example: Deposition of Silicon SiH4 + 2Cl2 = Si + 4HCl
Interfacial Reactions
Interfacial Reaction between Cu and Various Solder Experimental Observation ▶ Cu/Sn : Cu6Sn5 ▶ Cu/Sn-Pb eutectic : Cu6Sn5 ▶ Cu/Sn-Ag eutectic : Cu6Sn5 ▶ Cu/Sn-Zn eutectic : CuZn_γ ▶ Cu/Sn-In eutectic : Cu2(Sn,In) or Cu2In3Sn
Application to Solder/Substrate Interfacial Reactions – Cu/Sn Reaction
Application to Solder/Substrate Interfacial Reactions – Cu/Sn Reaction
Application to Thin Film Reactions – Metal/Si Reaction
Application to Thin Film Reactions – Metal/Si Reaction Sample Preparation Heat Treatment Measurement Amorphous First Silicide ref. crystal (111) triode d.c. sputtering bilayer (Ti: 95,400nm) isothermal (30min at 500oC) XRD/TEM - Ti5Si3 & TiSi 50 electron-gun deposition bilayer (Ti: 300nm) 120min at 500oC RBS aTiSi & TiSi2 51 polycrystal magnetron S-gun sputtering bilayer (Ti: 100nm) (40min at 600oC) XRD TiSi & TiSi2 52 <100> evaporation bilayer (Ti:100nm) (30min at 750oC) RBS/XRD 53 amorphous or <100> bilayer (Ti: 90nm) (20min at 450oC) Backscattering Spectroscopy TiSi 54 electron-beam evaporation bilayer (Ti: 3nm) (30min at 600oC) TEM 55 (100) conventional HV sputtering bilayer (Ti: 30nm) (60min at 650oC) RBS/TEM TiSi2 (C49) 56 electron-gun evaporation bilayer (Ti: 140nm) (120min at 550oC) RBS/XRD/TEM bTiSi2 57 trilayer (Ti: 10~100nm) (~300s at 560oC) yes SSA Ti5Si3 45 sputter-deposition a-Si/Ti/Si trilayer (Ti: 23nm) (60min at 500oC) TEM/RBS 58 sputter deposition bilayer (Ti: 25~35nm) (30min at 460oC) HRTEM/EDS 59 UHV e-beam evaporation a-Si/Ti/Si trilayer (Ti: 30nm) (30min at 450oC) in-situ RHEED /HRTEM cTi5Si3 60 poly Si rf sputtering bilayer (Ti: 55nm) heating (10oC/m) to 510oC XTEM/STEM 61 magnetron sputtering bilayer (Ti: 32,51nm) heating (15oC/min) to approx. 800oC IR-abs spect. XRD/resistivity 62 bilayer (Ti: 32,46nm) heating (3,20oC/s) in-situ XRD Ti5Si3/Ti5Si4 63
Application to Thin Film Reactions – Metal/Si Reaction
Application to Thin Film Reactions – Metal/Si Reaction
Application to Interfacial Reactions – Metal/Si Reaction
Thermodynamics Nano Materials Eunha Kim Inyoung Sa Byeong-Moon Lee and Byeong-Joo Lee Computational Materials Science & Engineering Lab. Pohang University of Science & Technology, Korea
Curvature Effect – Capillary Pressure System condition T = constant Vα = Vβ = V = constant @ equilibrium
Curvature Effect – Capillary Pressure Effect on Melting Point of Nano Particle
Melting points of Gold Nano Particles: B-J Lee, 2009
Melting points of Nano Particles: B-J Lee, 2009 Ni Pt Au W Mg Pt
Melting points of Nano Wires: B-J Lee, 2009 Ni Pt Au Mg W Pt
Motivation - in Collaboration with M.-H. Jo, POSTECH
Vapor-Liquid Liquid-Solid Reactions during the VLS Process SiH4 + GeH4 + H2 ② ① Vapor-Liquid Liquid-Solid
Vapor-Liquid Liquid-Solid Reactions during the VLS Process 200 torr SiH4 + GeH4 + H2 ② ① ① ② 200 torr 400 oC Vapor-Liquid Liquid-Solid
VLS Growth of Nanowires - GeSi Nanowires
Size dependence of SiGe nanowire composition
Size dependence of SiGe nanowire composition CALPHAD (2008)
Interfacial Phenomena – Segregation (Guttmann, Butler/Tanaka) Assume a one atomic layer surface phase and consider equilibrium between bulk and surface where ωi is the molar surface area Assume ωi = ωj = … = ω
Calculation of Surface Tension of Liquid Alloys
Calculation of Surface Segregation in Solid Alloys
Computational Thermodynamics as Materials Genome Computational Thermodynamics + First-Principles Calculation
Application to Metal/Ceramics Interfacial Reactions – Ti/Al2O3 Reaction
Application to Metal/Ceramics Interfacial Reactions – Ti/Al2O3 Reaction
Phase Field Simulation of γ→α transformation in steels Wetting angle : 36o Wetting angle : 120o Fe - 0.5% Mn – 0.1% C, dT/dt = 1 oC/s from SG Kim, Kunsan University
Computational Thermodynamics Summary Computational Thermodynamics Calculation of Multi-component Phase Diagrams Interfacial Reactions – Metal/Liquid Solder, Metal/Ceramics Thin Films Reactions – Metal/Silicon Thermodynamics of Nano Materials – Capillarity Effect