Thermal analysis of glass covered amorphous metal wire and amorphous ribbon

(G)lass covered amorphous metal wires (GCAW) of compositions Co66Fe4Ni1Si15B14, Co-68 Fe-28(4).32Si12.5B15, and Fe9Si19B12, and Fe9Si19B2 amorphous metal ribbon were thermally characterised using differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC), and thermogravimetric analysis (TGA). Additions of Co and Ni were found to increase the crystallization temperature from 541 degrees C for the FeSiB wire to 559 degrees C for the CoFeNiSiB wire. Both the FeSiB ribbon and wire possess two crystallisation peaks due to the crystallisation of alpha-Fe and Fe3B. The Curie temperature of FeSiB ribbon is easily found by DSC, while it is not visible in the GCAW, indicating that the glass covering acts as a barrier towards the detection of the Curie transition. The crystallisation temperatures for all of these materials coincide with the glass transition and the kinetics are far too rapid for it to be detected. Additions of Co and Ni decreased both the Curie temperature and the saturation magnetisation of the wires. Unusually high heat capacities were measured for the GCAW by MDSC and traditional DSC, while normal heat capacities were measured for the amorphous ribbon. Experimental results suggest that this anomaly may be due to a contact issue pertaining to the aspect ratio of the wire, but at the present time it is otherwise unexplained.