The Transformation of the Structure at Heating and Mechanism of Thermal Expansion of Sn-Bi Eutectic Alloy

The short range order structures of Sn-Bi eutectic melt has been studied by means of X-ray diffraction and reverse Monte-Carlo methods within 420 – 1120 К temperature range. Temperature dependences of interatomic distances and thermal expansion coefficient within first coordination sphere were calculated. Free volume temperature variation was investigated using Voronoi-Delone statistic-geometric method. Obtained data allowed us to find the occurrence of smeared structure transformation in Sn-Bi liquid eutectic and determine the temperature range of this transformation. Results of this study have a potential application in soldering technologies, particularly at improving of interface region properties. Kew words: short range order structure, thermal expansion, free volume.</span