Magnetically soft nanomaterials for high-temperature applications

Nanomaterials for high-temperature applications must meet two basic requirements: (i) very soft magnetic behaviour at elevated temperature, and (ii) stable properties at elevated temperature for a long time (application time). The latter requirement is related to thermal stability of nanocrystalline structure of these materials.The paper presents the current status of research in the field of magnetically soft nanocrystalline materials, highlighting the influence of alloy composition on magnetic properties and their stability at elevated temperatures during very long time annealing (several thousands of hours at temperature up to 550 °C). It was found that modification of the alloys allows to tailor their chemical composition and manufacturing process to particular application temperature requirements. FINEMETs are the most suitable materials for application at temperature, T, up to 300 °C, FINEMET modified by cobalt (Fe0.6Co0.4)73.5Cu1Nb3Si13.5B9 (at.%) for T = 300–350 °C, NANOPERM for T = 350–400 °C and HITPERM (Fe0.6Co0.4)86Hf7B6Cu1 for T = 400–550 °C.