Texture Simulation And Its Application In Magnetic Transformation

Texture has a huge impact on the material performance. The calculation andsimulation of texture has become an important branch of texture research and hasbeen extended to the engineering application. So it is of great significance to use thecomputer technology to calculate and simulate texture accurately and efficiently.Meanwhile, one can decrease experiment and shorten the experimental cycle bymeans of computer simulation. Magnetic transformation has significantly influence ofthe thermodynamic properties in a large variety of elemental materials andcompounds. But within the CALPHAD approaches for magnetic transformation, a lotof models are based on empirical assumptions, which have no physical meaning. Soseeking of theoretical models for magnetic transformation has a great theoreticalsignificance. As the texture that described the ordering of crystalline grain is similar tothe magnetic transformation that described the ordering of magnetic domain, methodsused in the simulation of texture are also useful in the description of magnetictransformation.Fiber texture diffraction patterns for texture axis index of <100>,<110>,<111>,<112> and texture deviation degree of0,0.6,0.8,1have been simulated by MATLABprocedures. In addition, standard stereogram for {001},{110},{111},{112} ofvarious kinds of crystal have been plotted by means of MATLAB calculations. TheX-ray refraction technique was used to identify the macro-texture of the cold rolledgrain-oriented silicon steel (30Q120). The results indicated that the steel plate existthe Goss texture {110}<100> and the Rotate Cube texture {001}<110>. TheMATLAB toolbox MTEX was used to analyze the pole figures of grain-orientedsilicon steel. Based on MTEX plotting routines, Orientation distribution function(ODF) in φ2section was plotted. A satisfactory agreement was reached between theexperimental data and the calculated data.The coefficients of linear thermal expansion (CLEs) of magnetic elements Fe, Coand Ni were assessed from experimental information using theoretical modelscombined with CALPHAD approaches. To facilitate the assessments, theories ofthermal expansion were applied to separate CLEs into its nonmagnetic and magneticcomponents. The calculations of nonmagnetic contribution to CLEs were based on the modified Grüneisen-Debye model, in which the Debye temperature was regarded asan undetermined constant. In order to put the prediction of CLEs at the magnetictransformation region on a sound physical basis, two kinds of theoretical models wereinnovatively used to calculate the magnetic contribution to CLEs, i.e. theBragg-Williams-Gorsky approximation and the Fermi-Dirac distribution function.Model parameters were evaluated from experimental data using least square method.Detailed comparisons were made with the published experimental data and thecalculated total CLEs. A satisfactory agreement was reached. Based on the methods oftexture simulation, the three-dimensional orientation distribution method wasinnovatively used to describe the magnetic domain, and a preliminary calculation ofthe spontaneous magnetostriction was also made in this work.