Magnetoelastic effects in single-, poly-, and nanocrystalline iron- and cobalt-based rare-earth alloys and their hydrides

Abstract

The magnetoelastic effects in intermetallic compounds with high contents of rare-earth and 3d transition metals are studied on (RR′R″)(Fe, Co)2, R2Fe14B, R2Fe17, and RFe11Ti compounds (R, R′, R″ = rare-earth metal (REM)) and their hydrides. The main laws of the formation of high magnetostrictive 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 RFe11Ti and R2Fe17 compounds (R = magnetoactive ion) are found to change the sign of magnetostriction. The sign of magnetostriction and Stevens factor αJ 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 R2Fe14B compounds. Magnetostrictive deformations are found to be highly sensitive to the structural state of all compounds under study.