Composites of poly(n-buthyl acrylate) (PnBA) and eutectic metallic alloy composed of Bi, In, and Sn were prepared by mechanically mixing them above the melting point of the metallic alloy, and glass transition temperature of PnBA. The heating curves of differential scanning calorimetry (DSC) of the composite of PnBA and the metallic alloy showed an endothermic peak below the melting point of the metallic alloy without polymers, which indicated the formation of the interfacial phases of the metallic alloy with a lower melting point. The exothermic peaks of the cooling curves were broadened and shifted to the temperature lower than the melting point of the metallic alloy without polymers, which suggests that the crystallization of the metallic alloy was suppressed by the interaction. The mechanism of lowering the melting points and suppression of the crystallization was discussed based on the results of DSC, transmitting electron microscopy, and X-ray diffractometry. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1278-1284, 2011