Phase analysis and structure of rapidly quenched Al-Mn systems

This investigation is focused on the rapidly quenched systems based on binary combination of post-transition and transition metal atom. The metastable Al-Mn alloys are prepared in form of metallic ribbons by planar flow casting and consequently used for elaboration of hard magnets. These systems are interesting as perspective alternative to RE based permanent magnets. The effect of alloying of constituting elements (in ratio about 1/1) on the changes of physical properties caused by structural transformations was studied. Magnetic properties result from the existence of phase τ-MnAl in the system. The structure evolution from as-cast state was analyzed by calorimetric and thermogravimetric measurements. The formation and evolution of crystalline phases is shown by direct structure observation using transmission electron microscopy and by X-ray diffraction methods. The results of in-situ phase analyses by exposure to a defined temperature regime are also presented. The annealing regime has a direct influence on magnetic properties, leading to small changes in coercivity and significantly affecting maximum energy product.