The influence of manganese on the glassy phase formation and evolution in Fe79.7−xMnxB20Nb0.3 rapidly solidified ribbons

The microstructure of Fe79.7−xMnxB20Nb0.3 glassy ribbons has been investigated using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), for manganese concentrations of x = 12, 16 and 20. In each case the ribbon is found to be amorphous with nanocrystalline inclusions. Using dark-field TEM, the mean size of the inclusions as well as their phase fraction, are measured and found to increase with manganese concentration. EDX mapping shows the tendency for manganese to form clusters several nanometers in size. Through detailed analysis of electron diffraction patterns, and in conjunction with JEMS simulation, the inclusions are shown to be manganese diboride (MnB2), and high resolution TEM investigation in conjunction with Single Crystal simulation confirms this.