Fundamentals of the Neutron Texture Analysis
Lecturer: Anatoly Nikitin
Specialty course
5th year (10th semester)
The goal of studying the discipline
The course is aimed at learning physical foundations of the interconnection between anisotropy and crystallographic textures of the polycrystal materials, namely, metals, alloys, composites, rocks, etc. acquaintance withmain experimental methods of studying the anisotropy of different properties and texture measurement using X-ray and neutron diffraction with the purpose ofusing these data bothin solving fundamental problems in the Earth sciences and for controlling properties of theconstruction materials.
Course contents
(16 two-hour lectures; two four-hour laboratory exercises)
Rock textures and their relation to geological and geophysical problems.
Crystallographictexturesandform textures. Textures of geomaterials of different scales. Main planetary evolution hypotheses. Relation of theevolutional mechanisms of thelithosphere with texture-formation. Usingthetextures as “rock chronicles” of theearth core. Texture analysis for solving theapplied tasks of geophysics.
Anisotropyandmaterialtextures.
Tensor quantities of different ranks. Anisotropic matter. Anisotropy of thetexture materials. Classification of the texture materials. Anisotropyofthemetalsandalloys.
Physical mechanisms of thetexture formation in polycrystals
Growth textures. Crystallizationofpolycrystals. Laws of crystallographic and geometric selection. Deformation textures. Plasticdeformation. Tensile strengthfor shifts in theideal and real crystals. Dislocation. Slidingin monocrystals and polycrystals. Formation of primary orientations for plastic deformation.
Physical mechanisms of texture formation (CONTINUATION)
Textures of recrystallization. Textures of theprimary recrystallization. Textures of thesecondary recrystallization. Textures of thedynamic recrystallization. Textures of theprecipitation. Influence on thephase transitionson thetextureformation. Texturesforming in melts.
Piezoelectric and magnetic textures.
The piezoelectric effect in artificial ceramics. Discovery of the piezoelectricity in rocks. Experiments confirming appearanceof thevolume piezoelectric effect forthepolycrystal rocks. Mechanisms of thetextures formationin rocks with thepiezoelectric properties. Texturescreatedbythemagneticminerals.
Theoretical foundations of the quantitative texture analysis
The notion of orientation. Definition of thedistributionfunction by orientations (DFO). PropertiesofDFO. Polarfigures (PF). An integralrelationbetweenDFOandPF. MethodsofreconstructingDFOfromexperimentalPF. TheRowe-Bunge method (expansion in the seriesof FSO and PF). Nonuniquenessof the solution oftheproblem. Alternative methods. Method of theapproximation of FSO by central normal distributionson SO(3). Method of thetexture components.
Probabilistic methods of the description ofpolyctrystal properties
Peculiarities of the structure of inhomogeneous materials. Notion of thematerial and field tensors. The procedure of averaging the properties. Random fields in the theory of micro-inhomogeneous substances. Methods of determinationof the material effective characteristics.
Indirect experimental methods of thetexture analysis and studying ofthe anisotropy of polycrystal properties
The magnetometric method. The ultrasound method of measuring the spatial anisotropy of the elastic properties of polycrystals in a wide range of pressures. The electrometrical method.
Experimental diffraction methods of thetexture analysis
The electronographic method. Theroentgenographicmethod. The neutronographic method on the impulse sources of neutrons and on the sources with continuous flow. The method of flighttime on theimpulse source.
The neutronographic texture analysis
Multi-detector neutron texture diffractometers. Geometry of the experiment. Resolution capacity of the device. Registration of the spectra and construction ofthe experimental polar figures. Reconstruction of DFO.
Neutronographic texture analysis in the Earth sciences
Seismic anisotropy. Investigation of the evolution processes in the earth crust and upper mantle. Reconstruction of the paleotectonic tensions in the blocks ofthelithosphere usingthe data on textures. New data on the structure and properties of the deep earth crustsubstance and mantle obtained by themethods of neutronography.
Neutronicinvestigations of thetexture of physical properties of thegeological materials under thermal and mechanical influences
Thermo-controllable camera of the one-axis compression in the complex with the neutron diffractometer SKAT on 7-th beam of the reactor IBR-2. Research of the texture, thermal and deformational properties of the marble with temperatures up to 250 ºС and the one-axis deformation. investigation of the inner tensions in the rock standards forthe one-axis deformation on the spectrometer epsilon. Investigation of the anomalous behavior of the properties of polycrystallic quartzite in temperature domainof theα–β phase transition.
Neutrongraphy and the physics of the earthquake centre
General notions of thephysics of the earthquakehearth. Models of thehearth and theproblem of forecast of the earthquakes. Development of theexisting models of thehearth and its dynamics with accounting ofthe new data about the changing properties of thesubstance atthe high pressures and temperatures.
Accounting the mechanisms combining the store of thehidden internal energy. Accounting the influence of the mass-transferof the fluid on big deepth and other factors.
Neutronographic texture analysis in the physical material science
The texture and anisotropy of the graphite. The texture and anisotropy of elastic properties of thedeformed iron-copper composite. Texture of salts and constructing materials. Texture of themeteorite substance.
Laboratory exercises
1. Preparation of samples for an experiment and measurement of diffraction spectra USING the SKAT diffractometer.
2.Experimental data processing. Spectrum indexing and identification. Drawing polar figures and reconstructing the orientation distribution function.