Morphology and phase transformation of nanoscaled indium-tin alloys in aluminium

Nanoscaled (In, Sn) alloy inclusions in Al matrix have been synthesized via rapid solidification processing route. Preliminary characterization of the samples has been done by X-ray diffraction. The microstructure of these alloy inclusions has been analyzed using transmission electron microscopy. Both In and Sn are immiscible with Al, and the miscibility gap can be accessed under rapid solidification conditions. In and Sn react with each other to form two intermediate phases, viz. beta and gamma respectively, which together form a eutectic. The morphology and orientation relationship of this beta-gamma eutectic system in nanoscale is reported here. TEM study reveals that majority of the alloy inclusions possess near cuboctahedral symmetry and that they are bicrystalline. Distinct two-phase contrast of these phases is observed in most cases. Melting and solidification characteristics of these alloy inclusions have been investigated via DSC. A melting peak at higher temperature is observed in the first cycle in addition to the eutectic melting event. Multiple solidification exotherms in the DSC is observed with maximum undercooling of 5degreesC in the present case. (C) 2003 Elsevier B.V. All rights reserved.