Minor additions of Sn in a bulk glass-forming Fe-based system

Minor additions of Sn in the bulk glass-forming Fe_61-xSn_xY₂Zr₈ Co₅Cr₂Mo₇B₁₅ (x = 0% to 2%) system were studied in detail. It was found that combinations of Y and Sn can scavenge oxygen out of the undercooled liquids to form innocuous oxides, thus stabilizing the liquids. Besides this beneficial scavenging effect, Sn additions in the present Fe-based alloys also showed complex alloying effects on glass formation, which can be divided into three stages. At stage I (x ≤ 0.5%), the microalloyed compositions associate with the same eutectic as that of the base alloy. The glass-forming ability (GFA) of the resulting alloys is determined primarily by their liquidus temperature and similar to that of the base alloy. At stage II (0.85% ≤ × ≤ 1.15%), glass-matrix composite structures start to form because the alloy compositions are adjusted into a new "deeper" eutectic system. At stage III (x > 1.15%), however, alloy compositions shift to another new eutectic system, and the GFA is dramatically decreased due to the strong formation of primary phase α-Fe. Homogeneous glass-matrix composites with a diameter of 7 mm in the alloy containing 1.0-1.15% Sn were successfully produced. © 2006 Materials Research Society.