Titanium diboride precipitation in Fe79.7−xTixB20Nb0.3 glassy ribbons

Abstract

The microstructure of Fe79.7−xTixB20Nb0.3 glassy ribbons has been investigated using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), for a titanium content of x = 12, 16, 18 and 20 at.%. With x = 12, the ribbon is found to be amorphous, with no sign of crystallinity. EDX mapping within the amorphous matrix, shows that iron and titanium are separated into iron-rich cells and titanium-rich inter-cellular channels. From x = 16, all samples contain nanocrystals embedded within the amorphous matrix. Using EDX, the nanocrystals are shown to be titanium-rich, and using electron diffraction and JEMS simulation, they are shown to be titanium diboride (TiB2). High resolution TEM investigation, in conjunction with Single Crystal software, confirms this. The size of the nanocrystals, and their phase fraction, are measured and found to increase with Ti concentration.