MTE2503

Phase equilibria and microstructure

6 points · 3 hours per week lectures/tutorials, 3 hours per week directed learning · First semester · Clayton

Objectives The objectives of the course are to develop an appreciation of the central role of phases and phase equilibria in governing the microstructure of engineering materials. The student will develop a strong understanding of the development and use of alloy phase diagrams from the laws of thermodynamics, especially the free energy concept. The importance of the linkage between equilibria, phase diagrams, microstructure and material performance is stressed. An appreciation should emerge that equilibrium thermodynamics is the standard methodology for interpreting microstructure in materials engineering but that phase changes and departures from equilibrium are often the most critical aspects of process intervention during manufacture.

Synopsis Application of thermodynamics Review of the gas laws, Joule-Thomson effect, reversibility and irreversibility, Carnot cycles, first and second laws of thermodynamics, statistical interpretation of entropy, phase transformations, Gibbs' free energy, Helmholtz free energy, Maxwell relations, heterogeneous reactions, reaction constants, Ellingham diagrams, fuel cells, Clausius-Clapeyron equation. The interpretation of microstructure Solid solutions, particle molar quantities, activity, positive and negative deviations from ideality, regular solutions, phase separation, chemical potential, equilibria and the phase rule, binary phase diagrams, computer-assisted simulation of phase diagrams and alloy microstructure, eutectics and eutectoids, peritectics and peritectoids, miscibility gaps, intermediate phases; the iron-carbon phase diagram. Construction and interpretation of ternary phase diagrams. Mass transfer in the solid state Fick's laws, vacancy diffusion, interdiffusion, Darken's equations, thermodynamic factors, Boltzmann factor. Evolution of microstructure Homogeneous and heterogeneous nucleation, thermodynamics of surfaces, nucleation and growth in the solid state, time-temperature-transformation curves, continuous cooling curves, non-equilibrium microstructures, crystallisation.

Assessment Assignments: 30% · Mid-semester test: 15% · Final examination: 55%

Recommended texts

Porter D A and Easterling K E Phase transformations in metals and alloys VNR, 1981

Back to the 1999 Engineering Handbook