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The theory of transformations in metals and alloys
01 Jan 1965-
TL;DR: In this paper, the authors present a general introduction to the theory of transformation kinetics of real metals, including the formation and evolution of martensitic transformations, as well as a theory of dislocations.
Abstract: Part I General introduction. Formal geometry of crystal lattices. The theory of reaction rates. The thermodynamics of irreversable processes. The structure of real metals. Solids solutions. The theory of dislocations. Polycrystalline aggregates. Diffusion in the solid state. The classical theory of nucleation. Theory of thermally activated growth. Formal theory of transformation kinetics. Part II Growth from the vapour phase. Solidification and melting. Polymorphic Changes. Precipitation from supersaturated solid solution. Eutectoidal transformations. Order-disorder transformations. Recovery recrystalisation and grain growth. Deformation twinning. Characteristics of martensic transformations. Crystallography of martensitic transformations. Kinetics of martensitic transformations. Rapid solidification. Bainite steels. Shape memory alloys.
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TL;DR: In this paper, it was shown that interdiffusion of Al and Ni leading to solid solutions precedes the formation of intermetallic crystalline compounds in multilayer films with various modulation periods and an overall atomic concentration ratio of three Al to one Ni.
Abstract: Solid‐state interdiffusion reactions at Al/Ni interfaces in multilayer films have been studied using differential scanning calorimetry, cross‐sectional transmission electron microscopy/microanalysis, and thin‐film x‐ray diffraction. Multilayer films with various modulation periods and an overall atomic concentration ratio of three Al to one Ni were prepared by alternate electron‐beam evaporation in high‐ and ultrahigh‐vacuum systems. We show calorimetric, microstructural, and compositional evidence that interdiffusion of Al and Ni leading to solid solutions precedes the formation of intermetallic crystalline compounds. Isothermal calorimetry indicates that Al3Ni subsequently nucleates in the interdiffused region at preferred sites. Calorimetric analyses also suggest that nucleation sites quickly saturate in the early stage of Al3Ni formation and that the nucleation site density strongly depends on the grain sizes of the deposited films. After coalescence into a continuous layer at the interface, Al3Ni thi...
219 citations
TL;DR: In this article, an imaging atom-probe combined with a high mass-resolution energy-compensated time-of-flight spectrometer has been used to study localised composition changes at the interfaces whose motion leads to the formation of bainite in steels.
218 citations
TL;DR: In this paper, the microstructural evolution during surface mechanical attrition treatment of cobalt (a mixture of hexagonal close packed (hep) and face-centered cubic (fcc) phases) was investigated.
218 citations
TL;DR: A critical overview of the conceptual background of the phase- field method, the most relevant fields of condensed-matter physics that have been approached using phase-field modelling, as well as the respective model formulations and the insight gained so far via their simulation and analysis are provided.
Abstract: Phase-field modelling is still a young discipline in condensed-matter physics, which established itself for the class of systems that can be characterised by domains of different phases separated by a distinct interface. Driven out of equilibrium, their dynamics result in the evolution of those interfaces which might develop into well defined-structures with characteristic length scales at the nano-, micro- or meso-scale. Since the material properties of such systems are to a large extent determined by those small-scale structures, acquiring a precise understanding of the mechanisms that drive the interfacial dynamics is a great challenge for scientists in this field. Phase-field modelling is an approach that allows this challenge to be tackled in a simulation-based manner. This review provides a critical overview of the conceptual background of the phase-field method, the most relevant fields of condensed-matter physics that have been approached using phase-field modelling, as well as the respective mode...
216 citations
01 Jan 1973
TL;DR: In this paper, the embrittlement due to 885°F (475°C) exposure was caused by precipitation of a chromium-rich α' phase on dislocations.
Abstract: The 885odgF (475°C) embrittlement of seven heats of chromium steels was investigated: four vacuum-melted heats with C + N 0.09 pet and 18 pet Cr, 18 pct Cr-2 pet Mo, or 18 pet Cr-2 pet Mo-0.5 pct Ti. The steels were heated at 600° (316°), 700° (371°), 800° (427°), 900° (482°), and 1000°F (538°C) for various times up to 4800 h and the influence of this aging was investigated by hardness measurements, impact tests, and electron metallography. It was demonstrated that the embrittlement due to 885°F (475°C) exposure was caused by precipitation of a chromium-rich α’ phase on dislocations. The nucleation rate of α’ was calculated with the aid of Becker’s theory and the results were used to extrapolate experimental data obtained in this study. After an exposure of about 1000 h at 1000°F (538°C), a decrease in room temperature toughness was observed for all steels investigated. The decrease in toughness was not caused by immobilization of dislocations by α’, but by precipitation of carbonitrides.
216 citations