1. Computational Thermodynamics
Byeong-Joo Lee
Computational Materials Science & Engineering Lab. Pohang University of Science & Technology

2. 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

3. Thermodynamic Modelling

4. Lattice Stability

5. Regular Solution vs. Quasi-Chemical Model

6. Thermodynamic Assessment – Cr-Ni Binary System
LfccCr,Ni = 8030 – ·T + (33080 – ·T)(1-2XNi)
LbccCr,Ni = – ·T + (34418 – ·T)(1-2XNi)
LliqCr,Ni = 318 – ·T + (16941 – ·T)(1-2XNi)
B.-J. Lee, 1992

7. Thermodynamic Assessment – Fe-Cr-Ni Ternary System
B.-J. Lee
1993

8. Thermodynamic Parameters (Fe,Cr,Mo)(Va,B,C,N)

9. Thermodynamic Modeling – Gibbs Energy
For a Phase with Formula Unit, (M1,M2,…,Mi,…)a(Va,C,N)c

10. Thermodynamic Modeling – Gibbs Energy
For a Phase with Formula Unit, (M1,M2,…,Mi,…)a(Va,C,N)c

11. 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 C2 = Binary Systems C3 = Ternary Systems C2 = Binary Systems C3 = Ternary Systems

12. Solution Models - liquid and fcc Fe-C alloys

13. Solution Model - liquid and fcc Fe-C alloys
fcc : (Fe)1(Va,C) 1
Liquid : (Fe,C)
Ternary (Fe,Mn)a(Va,C) c

14. Applications of Computational Thermodynamics

15. Thermodynamic Calculation – Practical Steels

16. 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

17. 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

18. Thermodynamics Assessment - Na-Al-H system

19. Assessment of thermodynamic properties in the Li-Al-H ternary system

20. Driving force of CVD Deposition
※ Example: Deposition of Silicon
SiH4 + 2Cl2 = Si + 4HCl

21. Interfacial Reactions

22. 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

23. Application to Solder/Substrate Interfacial Reactions – Cu/Sn Reaction

24. Application to Solder/Substrate Interfacial Reactions – Cu/Sn Reaction

25. Application to Thin Film Reactions – Metal/Si Reaction

26. 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

27. Application to Thin Film Reactions – Metal/Si Reaction

28. Application to Thin Film Reactions – Metal/Si Reaction

29. Application to Interfacial Reactions – Metal/Si Reaction

30. 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

31. Curvature Effect – Capillary Pressure
System condition
T = constant
Vα = Vβ = V = constant
@ equilibrium

32. Curvature Effect – Capillary Pressure Effect on Melting Point of Nano Particle

33. Melting points of Gold Nano Particles: B-J Lee, 2009

34. Melting points of Nano Particles: B-J Lee, 2009Ni Pt Au W Mg Pt

35. Melting points of Nano Wires: B-J Lee, 2009Ni Pt Au Mg W Pt

36. Motivation - in Collaboration with M.-H. Jo, POSTECH

37. Vapor-Liquid Liquid-Solid Reactions during the VLS Process
SiH4 + GeH4 + H2 ② ①
Vapor-Liquid
Liquid-Solid

38. 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

39. VLS Growth of Nanowires - GeSi Nanowires

40. Size dependence of SiGe nanowire composition

41. Size dependence of SiGe nanowire composition
CALPHAD (2008)

42. 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

43. Calculation of Surface Tension of Liquid Alloys

44. Calculation of Surface Segregation in Solid Alloys

45. Computational Thermodynamics as Materials Genome
Computational Thermodynamics + First-Principles Calculation

46. Application to Metal/Ceramics Interfacial Reactions – Ti/Al2O3 Reaction

47. Application to Metal/Ceramics Interfacial Reactions – Ti/Al2O3 Reaction

48. 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

49. 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