Nd60Fe30Al10 Glass Forming Magnetic Alloys: a Mechanical Spectroscopy Study at the 300- 560 K Temperature Range

H.SALVA; A. A. GHILARDUCCI; S.E. URRETA; L.M. FABIETTI; J.M.LEVINGSTON

DIFFUSION AND DEFECT DATA, SOLID STATE DATA. PART B, SOLID STATE PHENOMENA

Trans Tech publications

Lugar: Zurich; Año: 2012 vol. 148 p. 428 - 433

1012-0394

Abstract. The ferromagnetic amorphous phase in rapidly solidified Nd60Fe30Al10 glass formingalloys is investigated in melt spun ribbons (100 μm thick) and in chill cast cylinders (2 mmdiameter). The amorphous resulting for these two different quenching rates were characterized bytheir room temperature hysteresis loops, magnetization and differential calorimetric measurementsin the temperature range 300K-900K. The mechanical damping was explored in the 300-560 Ktemperature range, by measuring the internal friction and the shear modulus in a forced invertedpendulum operating in the frequency range 0.1-10Hz. Simultaneously, the electrical resistance ofthe samples was measured. The internal friction spectra of both, ribbons and a cylinder, exhibit alocal maximum at about 500K, arising in a relaxation mechanism. After some thermal cycles thepeak parameters stabilize reaching an apparent activation enthalpy of 1.5 eV and a limit relaxationtime τ0 ≈ 0.4-2.5 . 10-17s. In both samples, the electrical resistance largely decreases during the firstheating run to 560K and remains unchanged during subsequent thermal cycles. No changes in theelastic modulus or in the damping properties are detected at the Curie temperature of the alloys