Magnetoelastic Effects in Single-, Poly-, and Nanocrystalline Iron- and Cobalt-Based Rare-Earth Alloys and Their Hydrides

摘要

The magnetoelastic effects in intermetallic compounds with high contents of rare-earth and 3d transition metals are studied on (RR'R")(Fe, Co)_2, R_2Fe_(14)B, R_2Fe_(17), and RFe_(11)Ti compounds (R, R', R" = rare-earth metal (REM)) and their hydrides. The main laws of the formation of high magneto-strictive characteristics in the (RR'R")(Fe, Co)_2 compounds in different structural states are found. It is shown that hydrogenation of the compounds results in a substantial decrease in these characteristics. Hydrogenation and nitriding of the RFe_(11)Ti and R_2FE_(17) compounds (R = magnetoactive ion) are found to change the sign of magnetostriction. The sign of magnetostriction and Stevens factor α_J for R ions are found to correlate with each other, which indicates a prevalent contribution of the REM sublattice to the anisotropic magnetostriction of these compounds. New materials exhibiting invar properties are formed as a result of the incorporation of hydrogen atoms into the crystal lattice of the R_2Fe_(14)B compounds. Magnetostrictive deformations are found to be highly sensitive to the structural state of all compounds under study.