Mechanosynthesis of bcc alloys from Fe50−y/2Co50−y/2Sn y mixtures (2 ≤ y ≤ 33) and B2 ordering by annealing at modest temperatures

Abstract

of bcc alloys from Fe50-y/2Co50-y/2Sn y mixtures (2 ≤ y ≤ 33) and B2 ordering by annealing at modest temperatures. Hyperfine Interactions, Springer Verlag, 2017, 238 (1), article no 76 (13 p. AbstractElemental powder mixtures of Fe, Co and Sn of initial compositions Fe 50-y/2 Co 50-y/2 Sn y (2≤y≤26) are ball-milled at high-energy. They yield metastable alloys which are predominantly composed of a supersaturated bcc Fe-Co-Sn phase. The amount of tin dissolved in it is at least ~15 at.% in the dynamical conditions of milling which were selected. A recently discovered stannide, CoSn 5 , passed hitherto unobserved in Co-Sn binary phase diagrams. It forms at Co-Sn interfaces at very short milling times, 0.5h, thanks to the high-diffusivity of cobalt in tin. Finally, neutron diffraction and 119 Sn Mössbauer spectroscopy show that metastable B2 ordering develops in as-milled alloys, for y ≤ 26, when they are further annealed at modest temperature, here for 15h at 675K.The tendency to long-range order in ternary Fe-Co-Sn bcc alloys is thus observed in metastable alloys. KeywordsMechanical alloying, Fe-Co-Sn alloys, intermetallic compounds, B2 long-range order, Mössbauer spectroscopy, lithium-ion batteries