Kinetics of the Crystallization Process of Ferromagnetic Fe65.5Cr4Mo4Ga4P12C5B5.5 Bulk Metallic Glass

Abstract

Glassy rods of the multicomponent ferromagnetic Fe65.5Cr4Mo4Ga4P12C5B5.5 alloy were prepared by copper-mold casting technique under a protective argon atmosphere with diameters of 1.5 mm and 1.8 mm. As-cast samples were examined by non-isothermal analysis (DSC and DTA) and X-ray diffraction (XRD). The relatively high values for reduced glass transition temperature (Trg = 0.57) and supercooled liquid region width (ΔTx ≈ 60 K) indicate good glass forming ability (GFA) and high thermal stability of the undercooled liquid relative to the crystallization process. The numerous intermetallic compounds during the devitrification process were evolved. Set of three GFA parameters are obtained: α = Tx / Tl = 0.61; γ = Tx / (Tg + Tl) = 0.39; δ = Tx / (Tl – Tg) = 1.41. The Kissinger method was applied to evaluate the apparent activation energy and the frequency factor. The rate constant of the crystallization process is estimated by Arrhenius law. The following values are calculated: Ea = 418.03 kJ/mol; Z = 1.78•1027 min-1; kx = 1.56 min-1 (for 1.5 mm), and Ea = 375.48 kJ/mol; Z = 1.88•1024 min-1; kx = 1.44 min-1 (for 1.8 mm).