The influence of presetting α-Sn on the transformation of Sn at low temperature

α-Sn seed was preset on the surface of both the high purity tin (99.999%) and Sn-0.7%Cu ingots, then the samples were kept at -40 V for different times, the surface morphology of the samples was observed to study the process of the β/α transformation. SEM was used to evaluate the degree of the phase transition, while the XRD was applied to identify the product of the transformation The results showed that, without presetting α-Sn seed, there was no β/α transformation of the samples surface stored at -40 °C for nearly two months. But once the α-Sn was preset, even just contacting with the surface of the ingots, there had been tin pests within about an hour on the edge of high purity tin sample surface. Sn-0.7%Cu had the same phenomenon, but the transformation was not so fast. The reverse transformation α/β was measured by DSC, and the temperature is about 28 °C.