Structure Formation in Alloys

ISBN-13: 9781468415629 / Angielski / Miękka / 2012 / 141 str.

Il Ya V. Salli; Il Ya V. Salli

Opis

Properties of alloys are determined to a considerable extent by the form. the dispersity. the composition, and the quantitative relationships of the structural components. This monograph is an attempt to present the mechanism of the formation of the structure of alloys from the viewpoint of the most modern theory of phase transformations. The metastable state is treated at length be- cause there are few data in the literature up to the present time. The book concerns the conditions determining the creation of the different phases in alloys. The forma- tion of crystals of different compositions and dispersities is described. The cause of different degrees of metasta- bility of alloys, the mechanism of the transformation of metastable systems into the stable state, and other problems are analyzed. The most widely used alloys were investigated. The authors tend to avoid demonstrations based on cumbersome calculations and whenever possible replace them with conceptual models. Some of the problems described here resulted from discussions during the seminar of the Metal Science Faculty of the Dnepropetrovsk Metallurgical Institute, directed by K. P. Bunin. The basic experiments were made by the author in the laboratory of the Department of Metal Physics of Dnepropetrovsk State University in collaboration with E. V. Finagin, A. N. Shul'diner, E. Z. Graifer, E. . Psarev. . I. Pesetskii, V. 1. L'nyanyi and I. S. Miroshnichenko.

Spis treści

I. General Concepts of the Structure of an Alloy.- 1. Gaseous, Liquid, and Solid States.- 2. Solutions and Intermediate Phases.- 3. Shape of Structural Components, Defects, and Grain Boundaries.- 4. Structure and Properties of Alloys.- II. Some Concepts of Thermodynamics.- 1. Internal Energy and Entropy.- 2. Free Energy and Chemical Potentials.- 3. Thermodynamic Activity and the Activity Coefficient.- 4. Surface Energy.- III. Phase Equilibria and Phase Diagrams.- 1. Equilibrium Conditions of a System.- 2. Effect of Intermolecular Interaction on the Shape of the Phase Diagram.- 3. Solubility of the Phases of the Alloy.- 4. Intermediate Phases on the Equilibrium Diagram.- 5. The Approximation of the Theory.- IV. Nonequilibrium State.- 1. Metastability.- 2. Some Information on the Thermodynamics of Irreversible Processes.- 3. Problems of Kinetics.- 4. Coefficient of Diffusion and Heat Conductivity..- 5. Supercooled and Supersaturated Systems, Reaction Rates.- V. Mechanism and Kinetics of Phase Transformations.- 1. Formation of Nuclei.- 2. Crystal Growth.- 3. Different Types of Crystal Growth.- 4. Crystal Growth during Phase Transformation.- VI. Structure Formation in Alloys.- 1. Intracrystalline Liquation.- 2. Some Concepts of the Formation of the Structure of Alloys at High Degrees of Supercooling...- 3. Experimental Results on Structure Formation in Alloys Crystallized from Highly Supercooled Solutions.- 4. Singularities of the Crystallization Process of Alloys at High Degrees of Supercooling.- 5. Transformations in Systems with Intermediate Phases. Double Phase Diagrams.- VII. Kinetics of Coalescence and Determination of the Surface Tension at the Boundary of Solid Phases.- 1. Coalescence.- 2. Experimental Data on the Kinetics of Coalescence.- 3. Surface Tension at Cementite-Ferrite, Cementite-Austenite, and Graphite-Austenite Boundaries.- 4. Surface Tension at the Austenite-Ferrite Boundary.- 5. Approximate Equations for Determining the Values of Surface Tension.- VIII. Nonequilibrium Structure of Graphite-Forming Alloys.- 1. Formation and Growth of Graphite Nuclei.- 2. Surface Crystallization of Graphite and the Role of Defects.- 3. Method of Investigation.- 4. Carbon Due to Precipitation.- IX. Transformation of the Metastable System into the Stable State.- 1. The Stability of Metastable Systems.- 2. Rate of Transformation into the Equilibrium State.- 3. Carbon Due to Annealing.- References.