A traditional TG apparatus was modified by placing two permanent magnets producing a controlled magnetic field (TG(M): Magneto Thermogravimetry). This technique proved to be useful to study both structural relaxation and crystallisation of ferromagnetic metallic glasses. Results obtained for the amorphous alloys Fe40Ni40P14B6 and Fe62.5Co6Ni7.5Zr6Nb2Cu1B15, are reported in this paper. Structural relaxation can be evaluated by measuring changes in Curie temperature induced by thermal treatments. Crystallisation in TG(M) is detected through a change in the measured apparent mass (difference between the sample mass and magnetic force driving it upward). These results were confirmed by DSC analysis. Whether the obtained crystalline phase is ferromagnetic, it can be identified through its Curie temperature, measured by TG(M). In fact the value of 770degreesC measured as Curie temperature of crystallised Fe62.5Co6Ni7.5Zr6Nb2Cu1B15, led to conclude that the only ferromagnetic crystalline phase is alpha-Fe. These hypothesis was confirmed by XRD analysis, showing that the first crystallisation yields to alpha-Fe nanocrystals.
Thermal evolution of ferromagnetic metallic glasses - A study using TG(M) technique / Luciani, Giuseppina; Costantini, Aniello; Branda, Francesco; P., Scardi; L., Lanotte. - In: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY. - ISSN 1388-6150. - ELETTRONICO. - 72:(2003), pp. 105-111. [10.1023/A:1023907417059]
Thermal evolution of ferromagnetic metallic glasses - A study using TG(M) technique
LUCIANI, GIUSEPPINA;COSTANTINI, ANIELLO;BRANDA, FRANCESCO;
2003
Abstract
A traditional TG apparatus was modified by placing two permanent magnets producing a controlled magnetic field (TG(M): Magneto Thermogravimetry). This technique proved to be useful to study both structural relaxation and crystallisation of ferromagnetic metallic glasses. Results obtained for the amorphous alloys Fe40Ni40P14B6 and Fe62.5Co6Ni7.5Zr6Nb2Cu1B15, are reported in this paper. Structural relaxation can be evaluated by measuring changes in Curie temperature induced by thermal treatments. Crystallisation in TG(M) is detected through a change in the measured apparent mass (difference between the sample mass and magnetic force driving it upward). These results were confirmed by DSC analysis. Whether the obtained crystalline phase is ferromagnetic, it can be identified through its Curie temperature, measured by TG(M). In fact the value of 770degreesC measured as Curie temperature of crystallised Fe62.5Co6Ni7.5Zr6Nb2Cu1B15, led to conclude that the only ferromagnetic crystalline phase is alpha-Fe. These hypothesis was confirmed by XRD analysis, showing that the first crystallisation yields to alpha-Fe nanocrystals.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.