Effect of the remaining magnetization on the thermal ageing of high permeability nanocrystalline FeCuNbSiB alloys

In the context of increasing energy efficiency, manufacturers are developing more efficient electrical converters which are designed to operate at high temperatures. Indeed, the maximum reduction in mass and volume imposes a high compactness of the components inside the electrical systems. The magnetic materials which are in the heart of the electrical energy conversion are, therefore, exposed to work in severe environment of high temperatures and high frequencies (volume reduction). In this sense it is necessary to carry out ageing treatments of these magnetic materials under different operating conditions. The proposed paper studies the thermal ageing of high permeability nanocrystalline alloys under two magnetization conditions: with and without remaining magnetization. The high permeability nanocrystalline alloys of chemical composition Fe73.5Cu1Nb3Si15.5B7 were chosen. This ageing study is based on monitoring magnetic properties for four continuous thermal ageing treatments: 100, 150, 200 and 240 °C.