A new theoretical approach to the strain dependence of magnetic crystal-field anisotropy

We report on the derivation of analytical equations for ab-initio calculations of the strain dependence of crystal-electric-field (CEF) parameters for arbitrary deformations. The calculation is based on the fundamental assumption that the charge distribution deforms in the same way as the crystal. Based on this deformed-charge model, simple formulas for the practical usage are given for various site symmetries of cubic lattices under uniform strain. These formulas can be used to predict the change of the magnetic crystal-field anisotropy under strain, which is important for the design of magnetic materials and devices. As an example for the power of the method, we present a calculation of the magnetic contribution to the thermal expansion in some rare-earth-based materials.

The development of the method for identifying the hardening curves of materials based on the results of torsion tests of notched specimens

The article is devoted to studying the rheological properties of metals and alloys in a cold state. The method is proposed to identify the hardening curve of a material based on torsion tests of round specimens with a notch. Determining the hardening curve is based on measuring the coordinates of points on the surface of the specimen after testing and determining the corresponding value of the torque. Based on these values the coefficients in an equation for the stress-strain dependence can be determined by minimizing the derived functional. The paper proposes the algorithm for the numerical implementation of the new identification method. The results of the computer simulation confirmed its effectiveness.