Novel morphology and solidification behavior of eutectic bismuth–tin (Bi–Sn) nanowires

In the present work we show a simple and robust fabrication process for dense and continuous bismuth–tin (Bi–Sn) eutectic nanowires. The Bi–Sn eutectic nanowires of 200 nm diameter and several tens of μm in length were fabricated by a vacuum hydraulic force method. The alloy melt was injected into an anodic aluminum oxide (AAO) template to form nanowires after melt solidification. For this process, nanowires were formed from non-atomic deposition with liquid alloy; in this way, the composition of nanowires can be controlled precisely in stoichiometry. The Bi–Sn melt was restricted inside the AAO which has a low thermo-conduction and long period cooling rate around the melt. On the other hand, the heat flow is along the tube Z-axis and the melt is solidified from the AAO bottom to top because of the open pore on the AAO top. The eutectic nanowires were found to be dense and continuous with a uniform diameter throughout the length of the wires and with a lamellar microstructure along the wires’ Z-axis. In addition, the alternative segmental compositions showed that the ratio of tin to bismuth is approximately 3.3:1.