Undercooling of Eutectic Sn-57wt%Bi Alloy

Abstract

Rapid Solidification Processing (RSP), of metals and alloys, is establish by increasing of the undercooling applying high cooling rates (102 - 106 K/s) or by reduce nucleation sites using low cooling rates (1 K/s). Melt undercooling opens new solidification pathways for new nonequilibrium phases and unusual microstructures. Several techniques have been developed to reduce nucleation sites and produce increased undercooling in metals and alloys including the fluxing technique. The aim of this paper is to study the influence of the undercooling level on microstructures of eutectic Sn-57wt%Bi alloy by using the fluxing technique. A morphological change from eutectic to eutectic plus primary dendrites bSn was observed when the undercooling increase from 10 K to 19 K and a refinement of the primary dendrites bSn was observed when the undercooling increase from 19 K to 29 K. Increasing the undercooling led to a higher growth rate, hence morphological refinement occur.

Mechanically Assisted Low-Temperature Pyrolysis of Hydrocarbons

“…One may also create fractal interfaces mechanically at temperatures below the solidification temperature of the alloys, by using mechanical fracturing methods [5]. In the first case, the alloys are under-cooled by a convective heat transfer as is described in paper [6]. Such an under-cooling creates disordered dendritic fractal-like structures between the different phases in the alloys.…”