Processing, Microstructure And Magnetic Properties Of Alnico Ribbons

Since Alnico alloys are known as nanostructured metallic magnets, having a good corrosion and thermal stability, many research are devoted to find a miniaturization solution of this kind of permanent magnets in order to gain magnetic properties suitable to replace the permanent magnets containing critical elements, like Sm-Co and Nd-Fe-B permanent magnets, in the devices that requires lower performances and not so expensive routes for processing.The experiments consisted in preparation of ribbons samples from Alnico based alloy processed in an induction furnace. From the obtained ingot, there where process ribbons by melt-spinning technique. The obtained ribbons where then heat-treated and characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The coercivity of the as-spun ribbons was enhanced from 16.92 kA/m to 32.57 kA/m after heat treatment.A squarness ratio of around 0.6 is due the minor crystalline phases and to the residual stress induced by the rapid solidification process of the 2D structure of the ribbons, indicating a good candidate for radio-frequency identification (RFID), micro-electromechanical systems (MEMS) and other applications such as microwave circulators.