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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 article, a model is introduced based on a distribution of activation energies for the recrystallization process where each individual process follows ideal Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetics.
Abstract: The primary recrystallization of pure metals is mostly characterized by the standard Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetics. Data of the stored energy release during recrystallization of deformed copper are presented in this paper. In accordance with discussion in the literature they demonstrate however that this description of the transformation process is rather unsatisfactory. In particular, real materials often seem to lack the homogeneity of the deformed state as required by the JMAK-theory. Hence a model is introduced based not on a single but a distribution of activation energies for the recrystallization process where each individual process follows ideal JMAK-kinetics. The model is shown to work very well with data presented and allows a satisfactory prediction of either isothermal or non-isothermal transformation curves.
30 citations
TL;DR: In this paper, a set of models for predicting the diffusion-limited ice nucleation and growth inside biological cells were established Both the heterogeneous and homogeneous nucleation mechanisms were considered in the models Molecular mobility including viscosity and mutual diffusion coefficient of aqueous cryoprotectant (i, glycerol here) solutions was estimated using models derived from the free volume theory for glass transition.
Abstract: In this study, a set of models for predicting the diffusion-limited ice nucleation and growth inside biological cells were established Both the heterogeneous and homogeneous nucleation mechanisms were considered in the models Molecular mobility including viscosity and mutual diffusion coefficient of aqueous cryoprotectant (ie, glycerol here) solutions was estimated using models derived from the free volume theory for glass transition, which makes it possible to predict the two most important physical properties (ie, viscosity and mutual diffusion coefficient) over wide ranges of temperature and concentration as encountered in cryopreservation After being verified using experimental data, the models were used to predict the critical cooling rate (defined as the cooling rate required so that the crystallized volume is less than 01% of the cell volume) as a function of the initial glycerol concentration in a number of cell types with different sizes For slowing freezing, it was found that the requir
30 citations
11 Aug 2020-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a novel Cu-Cr-Yb alloy was designed and processed by thermo-mechanical treatment, and the microstructure, mechanical and electrical properties were investigated in detail.
Abstract: A novel Cu-Cr-Yb alloy was designed and processed by thermo-mechanical treatment. The microstructure, mechanical and electrical properties were investigated in detail. The results showed that the Cu-Cr-Yb alloy had a higher strength, a better softening resistance and a considerably high electrical conductivity than the Cu-Cr alloy. After 80% cold rolling followed by aging at 500 °C, the peak-aged Cu-Cr-Yb alloy had a Vickers hardness of 160 ± 1 HV, a tensile strength of 465 MPa, an elongation of 21.1% and an electrical conductivity of 89.5 %IACS, respectively. After a long-time aging at 500 °C, the nano-scale Cr-rich precipitates with FCC structure in the Cu-Cr-Yb alloy hardly coarsened. Thermodynamics analysis showed that the Cr-rich precipitates were inclined to nucleate with FCC structure, and the addition of Yb hindered the nucleation of the Cr-rich precipitates.
30 citations
TL;DR: In this article, the conditions for the incorporation of slip dislocations either propagating into a twin or engulfed by a growing twin are studied from the geometrical point of view.
Abstract: The conditions for the incorporation of slip dislocations either propagating into a twin or engulfed by a growing twin are studied from the geometrical point of view. The resulting dislocation formed in a twin is independent of the mechanism of the incorporation. Under suitable conditions no stacking faults are formed at the twin boundary. The decomposition of twinning dislocations forming the noncoherent twin boundary is described using complementary partial twinning dislocations. The theory is formulated for both type I and II twins. Compound twins are also briefly treated in the discussion. Using the tensor notation all the formulae are given in the form valid for all crystal structures.
30 citations
TL;DR: In this paper, a brief discussion is given of some of the important electron diffraction effects from steps and eptiaxial dislocations at interfaces, which can be extracted from the contrast.
30 citations