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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, large iron oxide microparticles with large sizes in the range of 1-5 μm have been facilely synthesized by a modified polyol method with NaBH4 as a versatile strong reducing agent.
Abstract: In the present research, large iron oxide microparticles with large sizes in the range of 1–5 μm have been facilely synthesized by a modified polyol method with NaBH4 as a versatile strong reducing agent. We found that the highly homogeneous iron oxide microparticles' novel structure is the best pure crystal phase of α-Fe2O3 in terms of polyhedral morphology and shape in existence. There are no diffraction peaks of other crystal phases from impurities in α-Fe2O3 microparticle products in the crystal growth. Interestingly, a new method of heat treatment or atomic surface deformation allowed for the discovery of a new large α-Fe2O3 structure with controlled specific α-Fe2O3 oxide grains in the crystal structure. The severe surface deformation of sharp, polyhedral, large α-Fe2O3 microparticles under a sintering treatment was found to give un-sharp, polyhedral large α-Fe2O3 microparticles with specific grains and boundaries.
33 citations
TL;DR: In this paper, the nucleation and crystal growth mechanisms of selected glasses from the GeS2-Sb2S3-CsCl ternary system have been investigated under non-isothermal condition.
Abstract: The crystallization of selected glasses from the GeS2–Sb2S3–CsCl ternary system has been studied under non-isothermal condition. The nucleation and crystal growth mechanisms have been investigated and proved to be dependant on the glass composition. It has been found that the 80GeS2–10Sb2S3–10CsCl is a good candidate for controlled crystallization. The best nucleation temperature and time have been determined. Crystals of about 20–30 nm have been uniformly generated in the glass and the obtained glass-ceramics have the same transmission in the mid and far infrared transmission.
33 citations
31 Aug 2000-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The morphology and substructure of lath martensites formed in β quenched dilute ZrNb alloys are described in this paper, where the laths are arranged in a nearly parallel manner within any given colony or packet.
Abstract: The morphology and substructure of lath martensites formed in β quenched dilute ZrNb alloys are described. The laths are arranged in a nearly parallel manner within any given colony or packet. Packets of alternately twin related laths and clusters of three mutually twin related lath martensite variants have been observed and the twinning plane is of {1 1 01}H type. With increasing niobium content a continuous transition from large colonies of lath martensites, through smaller lath colonies, to individual plates of the acicular martensites occurs. The lath–lath interface consists of regularly spaced parallel arrays of dislocations of 1 1 3>type. The habit plane traces of lath martensite lie close to {334} type poles and the operating lattice invariant shear mode is { 1 101}H 1 1 3>H shear system. This result is consistent with results predicted by the phenomenological theory. The preferred two and three habit plane variant grouping clustering is explained on the basis of self-accommodation effects.
33 citations
01 May 2006-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the ferrite grain nucleation mechanism during the austenite/ferrite phase transformation is studied in situ in the bulk of three different steel grades by three-dimensional X-ray diffraction (3DXRD) microscopy.
Abstract: The ferrite grain nucleation mechanism during the austenite/ferrite phase transformation is studied in situ in the bulk of three different steel grades by three-dimensional X-ray diffraction (3DXRD) microscopy. The main difference between the three steel grades is the carbon concentration. For each steel grade the ferrite fraction, nucleus density and nucleation rate are measured simultaneously during continuous cooling. By comparing the measured nucleation rate to the classical nucleation theory it is concluded that the activation energy for ferrite nucleation is about two orders of magnitude smaller than the current models predict for the three steel grades. During slow cooling the same nucleation behaviour is found for the three steel grades concerning the balance between the energy that is released by the elimination of interfaces and the energy that is required for the formation new interfaces during ferrite nucleation.
33 citations
TL;DR: In this paper, the evolution of the structure of the amorphous phase of Fe73.9 was investigated by a combination of wide-angle x-ray scattering, small angle xray scattering (SAXS), Mossbauer spectroscopy and X-ray absorption near edge spectrographs on the supposition that they would provide complementary information.
Abstract: An attempt has been made to investigate the evolution of the structure of the amorphous phase of Fe73.9 Cu0.9 Nb3.1 Si13.2 B8.9 (finemet) alloy by a combination of wide-angle x-ray scattering, small angle x-ray scattering (SAXS), Mossbauer spectroscopy and X-ray absorption near edge spectroscopy on the supposition that they would provide complementary information. Before the onset of nanocrystallization, the amorphous phase undergoes a structural relaxation resulting in small increase in the hyperfine field and a decrease in the width of the first diffraction maxima. There is an increase in the topological ordering in the system, though chemical inhomogeneity sets-in due to the clustering of Cu atoms in the pure amorphous state of this alloy. Annealing at 400 °C (well below the crystallization temperature) for different time durations results in occurrence of Cu clusters having fcc structure. Kinetics of Cu clustering is studied using SAXS. The incubation time for the clustering at 400 °C is ∼120 min. Wit...
33 citations