1st Edition

Mechanisms of Diffusional Phase Transformations in Metals and Alloys

    686 Pages 581 B/W Illustrations
    by CRC Press

    Developed by the late metallurgy professor and master experimentalist Hubert I. Aaronson, this collection of lecture notes details the fundamental principles of phase transformations in metals and alloys upon which steel and other metals industries are based.

    Mechanisms of Diffusional Phase Transformations in Metals and Alloys is devoted to solid-solid phase transformations in which elementary atomic processes are diffusional jumps, and these processes occur in a series of so-called nucleation and growth through interface migration. Instead of relying strictly on a pedagogical approach, it documents the evolution of phase transformation concepts. The authors present topics by describing a phenomenon and then following up with a corresponding hypothesis or alternative explanation. In this way, the book also shows how the field continues to evolve and meet new challenges.

    Integrated with information from a number of key papers and review articles, this volume reflects this revered and influential instructor’s unique and passionate way of introducing well-established theories and knowledge in a systematic way, at the same time introducing, in great detail, how a new idea or interpretation of a phenomenon has emerged, evolved, and gained its current status. If the published version of a theory or a model was too condensed, Aaronson worked the problem out in painstaking detail so that graduate students could follow the derivations. This collection is full of such unique "Aaronsonian idiosyncrasies," which add immense value as a powerful tool for learning in this challenging materials field.

    Applied Thermodynamics
    Free Energy-Composition Relationships for Binary Substitutional Solid Solutions
    Free Energy-Composition Diagram and Applications to Driving Force Calculations
    Thermodynamics of Interstitial Solid Solutions through Application to the Proeutectoid Ferrite Reaction in Fe-C Alloys
    Diffusional Nucleation in Solid–Solid Transformations
    Introduction through Qualitative General Statements
    Brief Comparative Survey of Nucleation in the Four Basic Types of Phase Transformation
    Outline of Approach for Development of Nucleation Theory
    Proof that the Equilibrium Concentration of Critical Nuclei Is Proportional to exp(_DG*=kT)
    Fictitious Equilibrium Nucleation Rate
    Derivation of Steady-State Nucleation Rate
    Estimation of b*
    Time-Dependent Nucleation Rate
    Feder et al.’s Treatment of t
    Time-Dependent Nucleation Rate for Homogeneous Nucleation with Isotropic g
    Ancillary Parameters
    Preliminary Consideration of the Approximation for f¼DGvþW
    Nonclassical Nucleation Theory
    Modifications of Homogeneous Nucleation Kinetics by Anisotropic Interfacial Energy
    Nucleation Kinetics at the Faces of Disordered Grain Boundaries
    Comparative Nucleation Kinetics at Grain Faces, Edges, and Corners Relative to Homogeneous Nucleation: Trade-Offs between N and DG* When gab Is Isotropic Nucleation at Dislocations
    Comparisons of Theory and Experiment
    Diffusional Growth
    Basic Differences between Diffusional Nucleation and Diffusional Growth
    A General Theory of Precipitate Morphology
    Disordered Interphase Boundaries
    Partially and Fully Coherent Interphase Boundaries
    Relative Growth Kinetics of Disordered and Partially Coherent Interphase Boundaries
    Metastable Equilibrium Phase Boundaries
    GP Zones
    Transition Phases
    Nucleation Sites
    Successive Reactions Involving Different Phases
    Precipitate Free Zones
    Coarsening (Ostwald Ripening)
    Overall Evolution of the Microstructure
    Massive Transformation
    Definition and History
    Phase Diagrams
    Overall Reaction Kinetics and the Existence Range
    Nucleation of Massive Transformation
    Growth Kinetics
    Interfacial Structure, Habit Planes, Orientation Relationships, and Growth Mechanisms
    Note on the Driving Force for Trans-Interphase Boundary Diffusion during Massive Transformation in a Two-Phase Field
    Cellular Reaction
    Definition and Introduction
    Systematics of Cellular Reactions
    Nucleation of Cellular Reactions
    Growth Kinetics of Cells
    Pearlite Reaction
    Crystallography, Nucleation, and Growth Mechanisms
    Edgewise Growth Kinetics of Pearlite
    Martensitic Transformations
    Salient Characteristics (Described Briefly)
    Thermodynamics of Martensite Transformation
    Overall Kinetics of Martensite Transformation
    Nucleation of Martensite
    Crystallography and Growth (or Propagation) of Martensite
    Bainite Reaction and Role of Shear in Diffusional Phase Transformations
    Three Definitions of Bainite
    Upper Bainite vs. Lower Bainite, and Inverse Bainite
    Sources of Carbide Precipitation


    Hubert Irwin Aaronson (Hub) received his BS, MS, and Ph.D. in metallurgical engineering at Carnegie Institute of Technology, Pittsburgh, Pennsylvania (now Carnegie Mellon University). He was a worldwide leader in the field of phase transformations of metals and alloys for more than half a century. He published more than 300 technical papers, organized numerous symposia and conferences, served a number of technical committees, and was recognized with many awards. He was a member of the U.S. National Academy of Engineering, Washington, District of Columbia; a fellow of both The Minerals, Metals and Material Society and ASM International; and an honorary member of the Japan Institute of Metals, Sendai, Japan. As R.F. Mehl Professor Emeritus at Carnegie Mellon University, Hub continued his professional activities to the very end until his passing in December 2005.

    Masato Enomoto received his BS and MS in physics from Tokyo University, and his Ph.D. from Carnegie Mellon University, Pittsburgh, Pennsylvania. He received many honors and awards both in the United States and in Japan for his research on phase transformations in metallic materials. He authored a book, Phase Transformations in Metals, in Japanese, and served on the editorial boards of several technical journals, including ISIJ International as editor-in-chief. He was elected a fellow of ASM International. He is currently a professor of materials science and engineering, Ibaraki University, Hitachi City, Japan.

    Jong K. Lee received his BS from Seoul National University, Seoul, South Korea; his MS from the University of Washington, Seattle; and his Ph.D. from Stanford University, California. He taught at Michigan Technological University, Houghton, for over three decades. He is a fellow of ASM International, and a foreign member of both the Korean Academy of Science and Technology and the National Academy of Engineering of Korea. He continues his research activities as a professor emeritus and research professor at the Department of Materials Science and Engineering, Michigan Technological University.