Structure and Microhardness of (Sn4In)100-Bix (x=0-8 at %) Alloys Produced by High-Speed Cooling

The phase composition, microstructure, mechanical properties and stability of foils of (Sn4In)(100-)Bi-x ( = 0-8 at %) alloys synthesized by the method of ultrafast quenching from the melt at cooling rates up to 10(5) K/s are studied. Rapidly hardened foils of (In4Sn)(100-)Bi-x alloys at a bismuth concentration of less than 4 at % consist of solid solutions of bismuth in the gamma phase (Sn4In) and tin, and foils of the (In4Sn)(92)Bi-8 alloy consist of a solid solution of bismuth in the gamma phase and tin, as well as the epsilon phase (BiIn). During aging of the foils at room temperature, the size of inclusions of the epsilon phase increases due to the decomposition of supersaturated solid solutions of bismuth in the gamma phase (Sn4In) and tin. The studied foils have a microcrystalline structure. The difference in the shape and size of the grains on the side of the foil adjacent to the crystallizer and the freely solidifying side is revealed. The texture of the gamma phase in foils depends on the concentration of bismuth. Doping of the gamma phase with bismuth leads to an increase in microhardness. Aging of the (InSn)(100-)Bi-x (x = 0, 2 and 4 at %) foils at room temperature for 30 h causes a steady increase in the microhardness.