This course focuses on the ability to understand the diffusion theory as a basis of the microstructure of metals and alloys, involving the formation mechanism and temperature and time dependent changes, from the viewpoint of phase equilibria and kinetics, and it also focuses on how the microstructural factors, such as lattice defects and phase interfaces, affect mechanical properties and functional properties of metallic materials. Physical, mechanical, and functional properties of metallic materials are governed not only by chemical compositions but also by materials’ microstructure in the multi length scale. First of all, physical and thermodymanical background is explained for phase diagrams which are necessary to understand microstructure formation. Then, students acquire how to correctly comprehend information related to the phase equilibrium and microstructure formation, and how to improve functions and properties of metallic materials by controlling microstructure including phase interfaces and lattice defects. Microstructure change is generally proceeds as the diffusion rate controlled phenomena at high temperature range in which atomic diffusion can be sufficiently activated. In this course, fundamental theory of diffusion is precisely explained for metals and alloys using simple mathematical approaches, for instance, how to solve the diffusion equation based on the Fick’s law is introduced. Moreover, the methodology will be discussed over how to understand the dynamical behavior of microstructure changes using solutions of the diffusion equation from the viewpoint of phase equilibrium. Note that, for the 2020 academic year, fundamental theory of diffusion in the first half, and phase diagrams and microstructure formation in the second half of the lecture.
By the end of this course, students will be able to:
1) Understand alloy phase diagrams, from binary to ternary systems, as a basis of microstructure, and to comprehend information related to the phase equilibrium correctly together with the understanding of thermodynamical background.
2) Explain the process of solidification microstructure depending on crystallographic orientation, and the processes of solidification and precipitation due to the heterogeneous nucleation, based on the understanding of the classical nucleation and growth theory.
3) Explain features of solidification microstructure of invariant reactions, eutectic and peritectic reactions, and to explain the relationship between eutectoid microstructure and mechanical properties of steels.
4) Explain the aging process of aluminum alloys including microstructure change due to the precipitation from supersaturated solid solution matrix and precipitation hardening mechanism, and also to explain the coherency of phase interfaces depending on the precipitation particle size.
5) Explain microstructure formed by the athermal martensitic transformation in steels, and shape memory effect and superelasticity originated from the thermal martensitic transformation in NiTi alloys.
6) Explain processes of recovery, recrystallization, and coarsening as temperature and time dependent changes of plastically deformed microstructure.
7) Explain features of fracture surface due to elastic deformation and brittle deformation, and features of dislocation substructure and fracture surface due to fatigue, cyclic deformation.
8) Explain the theory of diffusion phenominon based on Fick's law.
9) Explain the solution of diffusion equation and the determination of diffusion coefficient.
Phase diagram, Gibbs phase rule, Phase equilibrium, Phase transformation, Invariant reaction, Solidification, Precipitattion, Diffusion, Fick's law
|✔ Specialist skills||Intercultural skills||Communication skills||✔ Critical thinking skills||✔ Practical and/or problem-solving skills|
Exercise problems are assigned to students at the beginning of each class, and group discussion is held during the class according to topics to be learned. This course is devided in the first half and the second half, and understanding level is checked at the end of each half as midterm and final exams. Students should read the course schedule to check topics covered on that day, and preparation and reveiw are required.
|Course schedule||Required learning|
|Class 1||Free energy and nucleation-growth in solid solution||understand free energy in solid solution and explain the nucleation-growth mechanism based on classical nucleation theory.|
|Class 2||Diffusion in solid solution||understand Fick's first and second law stating that diffusion and diffusion flux under steady and non-steady states.|
|Class 3||Diffusional trans.; precipitation, eutectoid and massive trans.||understand diffusional transformations and classification based on local equilibrium theory.|
|Class 4||Martensitic transformation 1||understand martensitic transformation accompanied with atomic displasive and shear reaction.|
|Class 5||Martensitic transformation 2||understand a nature of martensitic transformation with matrix algebra.|
|Class 6||Recovery, Recrystallization and Grain growth||understand phenomenons with free energy change caused by lattice defects.|
|Class 7||Understanding level check-up examination 1, Review, and Supplement||Evaluate the understanding level for the first half of this lecture (Class 1 through 6) by examination, and review the topics for insufficient understanding level.|
|Class 8||Phase Equilibrium and Phase Stability in Binary Phase Diagrams||Understand how to comprehend binary phase diagrams about phase stability and phase region, and explain phase equilibrium conditions using chemical potential together with thermodynamical meaning.|
|Class 9||Solidification and Microstructure Development||Explain heterogeneous nucleation with understanding of classical theory of nucleation and growth. And explain the relationship between crystallographically preferred growth direction and dendritic growth.|
|Class 10||Invariant Reactions and Microstructure Formation in Binary Systems||Explain formation of microstructure by binary invariant reactions; eutectic and eutectoid reactions, and peritectic and peritectoid reactions. Also explain how to expand from binary to ternary system in terms of invariant reactions according to the Gibbs phase rule.|
|Class 11||Expansion of Phase Diagrams from Binary to Ternary Systems||Comprehend alloy compositions, isotherms, and isopleths of ternary phase diagrams, and explain phase equilibrium condition in ternary systems, as extended from binary systems.|
|Class 12||Invariant Reactions and Reaction Schemes in Ternary Systems||Comprehend three types of invariant reactions, reaction schemes, and projections of liquidus surface of ternary phase diagrams, and explain phase equilibrium condition in ternary systems.|
|Class 13||Temperature- and Time-Dependent Change of Microstructure, and Fracture||Understand changes in microstructure due to precipitation and coarsening, and process of recovery and recrystallization after severe plastic deformation. Explain the characteristics of fracture surface formed depending on fracture modes such as ductile, brittle, cyclic fatigue and so forth.|
|Class 14||Understanding level check-up examination 2, Review, and Supplement||Evaluate the understanding level for the first half of this lecture (Class 8 through 13) by examination, and review the topics for insufficient understanding level.|
To enhance effective learning, students are encouraged to spend approximately 100 minutes preparing for class and another 100 minutes reviewing class content afterwards (including assignments) for each class.
They should do so by referring to textbooks and other course material.
Nishizawa, Taiji. Tamura, Imao. Sudo, Hajime. Metallography (Kinzokusoshikigaku). Tokyo: MARUZEN Co.,Ltd.; ISBN-13: 978-4621082430, (Japanese), Nishizawa, Taiji. Thermodynamics of Microstructure (Mikurososhiki-no-Netsurikigaku). Sendai: The Japan Institute of Metals and Materials; ISBN-13: 978-4889030280. (Japanese)，Kohda, Shigeyasu. Introduction to Metal Physics (Kinzoku-buturigaku-joron). Tokyo: CORONA Publishing Co.,Ltd.; ISBN-13: 978-4339042870. (Japanese).
Students' knowledge of followings will be assessed; diffusion related laws, solution of the diffusion equation, analysis of diffusion coefficient, comprehension of phase diagrams regarding microstructure formation as phase equilibrium, kinetics of microstructure formation, microstructure formation processes through solidification, precipitation, phase transformation. Understanding level check-up test and final exam 60%, and exercise problems 40%. The first half classes 50% and the second half classes 50%, and credits require 60 scores and higher out of 100.
Kimura: kimura.y.ac[at]m.titech.ac.jp, 045-924-5157
Nakada: nkada.n.aa[at]m.titech.ac.jp, 045-924-5622
Will be noticed on the first day of the lecture. It is basically recommended to contact by e-mail or telephone in advance to schedule an appointment.