Cristallisation kinetics of B-rich Miscmetal-Fe-B nanocomposite ribbons

C. E. RODRIGUEZ TORRES; F. D. SACCONE; G. A. PASQUEVICH; M. B. FERNÁNDEZ VAN RAAP; F. H. SÁNCHEZ

Buenos Aires

Congreso; At the Frontiers of Condensed Matter II; 2004

In a previous article [1], it was reported that Nd3Fe79B18 melt-spun and subsequently crystallised nanocomposite ribbons had a coercivity value Hc= 200 kA/m. After the controlled annealing, it was found that t-Fe3B and α-Fe had precipitated containing a dilution of Nd atoms in the boride structure. This fact promoted a magnetic hardening of t-Fe3B phase due to an increase of its magnetocrystalline anisotropy. It was concluded that B-rich nanocomposite ribbons with a composition of RE2.5Fe79B18.5, are at the onset of the RE content range which would promote their magnetic hardening. In this work, the M¨ossbauer thermal scan analysis method [2] was employed to follow the crystallisation kinetics of MM2.5Fe79B18.5 (MM: Mischmetal) and the results were compared with those obtained by other techniques, such as thermomagnetic measurements and differential scanning calorimetry. The evolution of the crystalline phases fraction (in this alloy, Fe2B and α- Fe) was also determined by M¨ossbauer spectroscopy performed during isothermal annealing at 550 ◦C.   ——————– [1] B. X. Gu, J. Magn. Magn. Mat. 263, 332-336 (2003). [2] P. Mendoza Z´elis, G. Pasquevich, F.H. S´anchez, N. Mart´ınez y A. Veiga. Phys. Lett. A 298, 55-59 (2002).