Melting Behavior of Sn-Bi Alloy Droplets during Continuous Heating.

摘要

An increase in the heating rate applied to samples of bct solid solution alloys in the Tin-Bismuth system was observed to bring about a change in the melting behavior in that an additional melting event appeared between the equilibrium solidus and liquidus temperatures. The measured temperature of this reaction was interpreted as corresponding to invariant melting of retained Beta of composition C(o) at the T(o) temperature. A comparison of the measured values with the T(o) calculated from thermodynamic analysis showed good agreement (within 1.5C). A mechanism involving sluggish diffusion in the solid is proposed to account for the retention of C(o) solid up to its corresponding. T(o) temperature. Moreover, the observed melting behavior has direct relevance to understanding the influence of the recalescence thermal history on the microstructural development during rapid solidification of highly undercooled liquids. Keywords: Powder metals; Binary alloys; Partitionless reactions; Reprints. (AW)