The precipitation of nanocrystalline structure in The Joule heated Fe 72Al 5Ga 2P 11C 6B 4 metallic Glasses

Abstract

In this study, the evolution of the nanostructure on dc Joule heated Fe 72Al 5Ga 2P 11C 6B 4 metallic glass ribbons have been investigated. Heating power per square area (PS) was ranging between 0.8 to 7.1 W/cm 2 in order to get various stages of relaxation or nanocrystallization. The crystallization starts after applying PS ≈ 4.35 W/cm 2 and the sample consist of residual amorphous matrix, a magnetic crystalline component and also a non-magnetic crystalline component (relative abundance of Fe in the crystalline phase is about 35%). XRD measurements show that crystalline samples after current annealing consist of Fe 3B, FeC, FeP and Fe 3P compounds. On TEM micrograph a broad distribution of shapes and sizes is noticed, the latter range from about 60 to 350 nm, increasing by applied heating power. The decrease of the electrical resistivity after each current annealing treatment is rather small in comparison with other Fe-based amorphous alloys (only about 1.5 % for the highest P S). Partial nanocrystallization leads to increase of coercive field (from H C ≈ 7 A/m in the amorphous as-cast state up to 45A/m) attributed to precipitation of magnetically harder compounds (Fe 3B and FeC).