Influence of HDDR treatment on magnetic properties of TbFe2- and DyFe2-based intermetallics

Magnetic properties of TbFe₂, DyFe₂, Tb(Fe_0.8M_0.2)₂ and Dy(Fe_0.8M_0.2)₂ with M=Co, Al, Si, Ga alloys affected by the Hydrogenation-Decomposition-Desorption-Recombination processing have been studied. After hydrogen treatment the coercive force H_c grows sharply, so HDDR-powders can be used as isotropic permanent magnets with the energy product up to 26 MG Oe at T=77 K. In Dy(Fe_0.8Al_0.2)₂ at T<10 K the stepwise magnetic reversal has been observed. The HDDR-treatment increases the critical field of magnetic reversal from 11 up to 18.4 kOe at 4.2 K. It is shown that the effect of the stepwise magnetic reversal is caused by a heat release in a sample during an avalanche motion of narrow domain walls.