Tracer Diffusion Data for Metals, Alloys, and Simple Oxides

ISBN-13: 9781468460773 / Angielski / Miękka / 2012 / 108 str.

John Askill

Opis

Atomic diffusion in metals was first discovered some sixty-five years ago, and since then a considerable wealth of data has ac cumulated on diffusion in various systems. However, work prior to about the year 1940 is now mainly of historical interest, since ex periments were often carried out under experimental conditions and with methods of analysis leading to uncertainties in inter preting the measured diffusion coefficients. Data on diffusion rates are of importance in processes which are controlled by rates of atomic migration such as growth of phases and homogenization of alloys. In addition diffusion plays an important part in theories of such phenomena as oxidation, plastic deformation, sintering, and creep. A tremendous advance in diffusion studies was made possible by the availability of radioactive isotopes of sufficiently high spe cific activity after the second world war. Measurements of self diffusion rates then became possible using radioactive isotopes having the same chemical properties as the solvent material, and it also became possible to study tracer impurity diffusion when the concentration of the impurity is so small as not to alter the chemi cal homogeneity of the system. In the last ten to fifteen years the purity of materials used in diffusion studies has increased con siderably and the methods of analysis have become more stand ardized."

Spis treści

1 Diffusion, the Diffusion Coefficient, and Mechanisms of Diffusion.- 1. Diffusion.- 2. The Diffusion Coefficient.- 3. Solutions to the Diffusion Equation.- 4. Methods of Analysis of the Diffusion Samples.- 4.1. Serial Sectioning.- 4.2. Residual Activity Method.- 4.3. Surface Decrease Method.- 4.4. Autoradiography.- 5. The Temperature Dependence of the Diffusion Coefficient.- 6. Mechanisms of Diffusion.- 6.1. Vacancy Mechanism.- 6.2. Interchange of Exchange Mechanism.- 6.3. Ring Mechanism.- 6.4. Interstitial Mechanism.- 6.5. Interstitialcy Mechanism.- 6.6. Crowdion Mechanism.- 6.7. Dislocations.- 6.8. Grain Boundary.- 7. Summary of Terms.- 8. Suggested Further Reading.- 2 Empirical and Semi-Empirical Diffusion Relations.- 1. The Dushman and Langmuir Relation.- 2. Simple Empirical Correlations Between the Self-Diffus ion Activation Energy and Various Properties of Metals.- 2.1. Melting Point.- 2.2. Latent Heat of Fusion and Sublimation.- 2.3. Compressibility.- 2.4. Coefficient of Linear Expansion.- 3. Relations Involving Elastic Moduli.- 4. An Extended Melting Point Correlation.- 5. Empirical Relations for Impurity Diffusion and Self-Diffusion in Alloys.- 6. Summary of Empirical Relations.- 3 Radioactive Tracer Diffusion Data in Metals, Alloys, and Oxides.- 1. Introduction.- 2. Some Predicted Diffusion Parameters.- Tables.- I. Self-Diffus ion in Pure Metals.- II. Impurity Diffusion in Pure Metals.- III. Self- and Impurity Diffusion in Alloys.- IV. Self- and Impurity Diffusion in Simple Metal Oxides.- References.- Author Index.- General Index.