
Research: Crystallography of Twinning; Advanced Materials
Academic Preparation:
Doctor of Physics (Ph.d), 1995, Georgian Technical University, Tbilisi Georgia. Dissertation: The Crystallographic Theory of Twinning and Computer Simulation.
Candidate of Sciences, 1977, GTU.Thesis: Structural Transformations During Ordering in CuPd and FePd Alloys
Institution: GIXI ingenierie informatique, Paris, France. Software course.06.1981  07 1981; Certificate (Attestation de stage).
Institution: Institute of Improvement of Skill of Information Workers (Specialty: International Systems of Scientific Information), Moscow, Russia.09.197910 1979; Certificate.
Institution: Graduate student at the Institute of Physics of Metals and Materials Science, (CNII Ch.M.), Moscow, Russia.09.1971  06.1972.
Institution: State Courses of Foreign Languages (English) Tbilisi, 09 1974  07 1975; Certificate.
Institution: Georgian Technical University, Tbilisi 09 1967  07 1972; Diploma of Engineer Physicist.
Professional Appointments:
1996 (current): Professor of Physics at the Georgian Technical University. Research: structural phase transformations in solid state; crystallography and computer simulation of diffraction processes; Lecturer
19921996: Leading research fellow at the Republic Center for Structure Researches (RCSR), GTU.
19871992: Head of the Sector for Computer Simulation of Physical Processes at RCSR, GTU.
19821987: Senior research fellow at the Republic Center for Electron Microscopy, GTU.
19801982: Senior research fellow at the Radiochemical Laboratory of the GTU. 19741980: Junior research fellow at the Radiochemical Laboratory of the GTU. 19721974: Assistant at the Department of General Physics, GTU.
Temporary appointments:
Summer 1977: Sabbatical at the Institute of Physics and Materials Science (CNII Ch.M.), Moscow, Russia.
Sept.75July 76: Visiting Scientist at the Institute of Physics of Metals, Kiev, Ukraine.
Publications: 99, in Russian and in English. (incl. 2 guide books for students on Xray characterizations and electron diffraction; in Georgian).
Professional societies: Georgian Physical Society; Georgian Academy of Ecology; Member of British Computer Society; Incorporated in the World Directory of Crystallographers
Language skills: Georgian (native), Russian(fluent), English(very good), German (poor).
Crystallography of twinning in crystals
Prof. Dzigrashvili has developed a method of calculation of twinning modes and the Analytical Theory of Crystallography of Twinning providing prediction of the twinning elements from a knowledge of twinning plane and metric tensor of the crystal lattice.
Prof. Dzigrashvilis current research involves investigation and proof of the regularity found by him for twinning shear plane in compound twins. The regularity is formulated in the form of certain transformation (mapping). As a result a new procedure for determining the twinning shear plane and shear direction, from a knowledge only of twinning plane and the metric tensor of the crystal lattice is proposed. The transformation equation describing a specific mapping (SM) is proposed, which transforms a set of arbitrary vectors into a set of coplanar vectors, situated in the plane of the twinning shear. Miller indices of the shear planes and the indices of corresponding shear directions defined by this method for twinned crystals coincide with the experimental data. The analytical treatment based on the general theory (GT) of deformation twinning is shown, in order to test the accuracy of the suggested mapping. Agreement between the two (SM, GT) approaches was found to be excellent.
Mapping (1) transforms any set of arbitrary, generally noncoplanar, vectors u into a set of coplanar vectors D u, situated in the plane of twinning shear P. Thus, knowing the couple of D u , one can easily find the covariant components of the normal to the plane P, i.e., the Miller indices of P, as a vector product of the contravariant components of any couple of vectors D u. Then, taking into consideration the geometry of twins, the intersection of P with the plane of twinning K_{1}, gives the direction of the twinning shear .
D u_{ }= (IR)^{t }u_{ }(1)
Here, I is an identity matrix; R = Ds _{k}; D is a mirror reflection matrix for the given twinning plane, and s _{k }is a matrix of mirror reflection in the plane normal to the kth principal axis of the crystal lattice, so that s _{x }s _{y} and s _{z}, represent the reflections in the planes normal to the axes [100], [010] and [001] respectively. Superscript t denotes transposition of the matrix.
Thus, by direct calculations it was shown that substitutions for s _{k} (s _{x}, s _{y}, s _{z}), in the relation (1), result in the three sets of covariant (reciprocal space) components of the normals to the possible three alternatives of P, and at least one of the sets represents the Miller indices of the operative plane of shear.
For practical application of the developed approach one may simply follow a hypothesis that in compound twins the shear plane P corresponding to the plane of twinning K1 contains not only the normal m to K1, as it follows from the definition of the plane P, but also one of the conventional basis vectors n = [100], [010] or [001] of the lattice, as a consequence of the proposed approach.
Actually the following algorithm may be used for calculation of twinning shear direction:
Generally, one of the three calculated values of _{1} (with rational indices) coincides with the experimentally determined one, with the accuracy of sign. Sure, for cubic crystals all the three values are operative because of symmetry. Here are some calculated examples in the table below.
Twinning modes calculated using the formulae given in [21] (Microscopy and Analysis, 2008), and some supporting experimental data
Notes:  experimental data not available to the author
* morphological system
1) exact value, (1 0.06 0).
2) exact value, (1 3.991 0)
The crystallographic data are taken from:
N.V. KlassenNeklyudova: Mechanical Twinning of Crystals. Plenum Press, NY 1964.
Kelly, A.; Groves. G.W.: Crystallography and Crystal Defects. Longman, London 1970.
Christian, J.W.: The Theory of Transformations in Metals and Alloys. Pergamon Press,
Oxford 2002.
www.webmineral.com
www.webelements.com
Computer generated schemes include crystal lattice parameters, direction of incident beam (zone axis), reciprocal lattice vectors, indexed scheme of diffraction pattern in readable scale and the same scheme in scale of microscope's l L. The program pack generates stereographic projections of directions and gnomostereographic projections of planes.
Prof. Dzigrashvili's research efforts focus on the following directions of Materials Science:
Structure of small particles of Boron  
Computer simulation of structure of small particles (classical approach based on 612 potential of interatomic interaction).  
Structure of whisker crystals of Boron  
Corrosion of Chromium  
Structure of highcarbon steels and austempered ductile iron 
1. Method of Derivation of Twin Relation Matrices for the Analysis of Electron Diffraction Pattern from Crystals of any System. Kristallografia, (1975), v.20, N5, p.p.965 968 (in Russian).
2. Diffuse Scattering of Electrons and lattice Instability in CuPd Alloy. Izvestia Vuzov SSSR, Fizika, (1976), N1, p.p.149 152 (in Russian).
3. Structural Changes During Ordering of Fe50at%Pd alloy. Fizika Metallov i Metallovedenie, (1977), v.43, N6, p.p. 13161319 (in Russian).
4. Peculiarities of Physical Properties and Ordering in CuPd Alloys. Fizika Metallov i Metallovedenie, (1978), v.45, N6, p.p.12001202 (in Russian).
5. Computer Simulation of Electron Diffraction Patterns from Twinned Crystals. Kristallografia, (1980), v.25, N5, p.p.10601061 (in Rusian).
6. Computer Simulation of Electron Diffraction Patterns and Stereographic Projections for the Analysis of TwoPhase Crystals. Kristallografia, (1984), v. 29, N6, p.p1190 1190 (in Russian).
7. Charasteristics of Electron Diffraction on Cementit Lattice Proceedings of 5th Conference on Applied Cristallography. Vol.1 Kozubnik, Poland. September 1014. 1984. p.p. 244248.
8. Electronmicroscopy Investigation of the Structure of Amorphous Boron. American Institute of Physics. Sov. Phys. Solid State 27(5) 1985.
9. Determination of the Mean Inner Potential of Singlecrystal Lattices of BoronContaining Materials and Its Relation to the Work Function. Elsevier, Sequoia, “Journal of LessCommon Metals”. 117,(1986) p.p. 283286.
10. Electron Microscope Investigation of the Processes of Crystallization of ZrO_{2} Amorphous Films Prepared in SuperHigh Vacuum. ZIRCONIA'88 Advanced in Zirconia Science and Technology 7^{th} SIMCERInternational Simposium on Ceramics, ZIRCONIA’88 December (Edited by S. MERIANI University of Trieste). Bologna (Italy) December 1416 1988 p.131135 ELSEVIER, LONDON, NEW YORK.
11. Crystallography of Twinning of Batch Martensite and Internal Tension. Fizika Metallov I Metallovedenie, (1989), v.67, N3, p.p.518524.
12. Peculiarities of internal Friction in Boron Carbide. AMERICAN INSTITUTE OF PHYSICS CONFERENCE PROCEEDINGS 231. BoronRich Solids ALBUQUERQUE, NM 1990, pp. 594601 New York.
13. Physical properties and Structure of FerroelectricFeroelastic DMAAS Crystals. Proceedings of the International Symposium “Structure and Properties of Crystals. Moscow, 1991 July. Butll. Soc. Cat. Cien. Vol. C III, Num.1, 1992, Spain.
14. The crystallographic calculation of the elements of mechanical twinning in crystals. Zeitschrift fur Kristallographie (1995), 210, pp. 167172. R.Oldenburg Verlag, Munchen.
15. The Analytical Theory of The Crystallography of Mechanical Twinning Ferroelectrics, Vol.175 pp.111(1996) U.S.A.
16. Electron Microscopic Study of The First Stages of Martensite Decomposition in Carbon Steel. Georgian Engineering News (1999), N1, p.p.515.
17. New HighStrength Deformable cast iron For Producing Wares by Pressing, Forging and Casting. Georgian Engineering News, (2000), N3, p.p.3944.
18. Structural Mechanisms of Relaxation of Stresses During ShearLike Transformation in HighCarbon Austenite. Proceedings of the International Metallurgy and materials Congress, Istanbul, Turkey, 2428 May, 2000, p.p. 19751982.
19. Some Physical Properties of Compacted Specimens of Highly Dispersed Boron Carbide and Suboxide. Elsevier. Journal of Solid State Chemistry 177 (2004), p.p.596599.
20. Interpretation of Electron Diffraction Patterns of TwoPhase and Twinned Crystals. Inteleqti Publishing House, Tbilisi, Georgia, (2005) 197p.(In Russian)
21. Computer Simulation of Electron Diffraction Patterns and Stereographic Projections. John Wiley & Sons LTD, Chichester, UK. Microcopy and Analysis, January (2008) p.p. 57.
22. The Analysis of Microcrack Plastic Zone Formed in the Films After LCF Tests of Austenitic Steel Used in NPP I. Trans tech Publications, Switzerland. Key Engineering Materials Vols. 417418 (2010) p.p.109112.
23.SEM Study of HighChromium Martensitic Steel LCF Fracture. TransTech Publications, Switzerland. Key Engineering Materials Vol. 465 (2011), p.p. 298301.
24.Study of Fracture Mechanisms at Cyclic Fatigue of Steels Used in Nuclear Reactors I. Steel Research International. V. 83, #3, 2012, p.p. 213217.