THE radial uniformity of components is an important parameter for crystal growth of a semiconductor of binary alloy. Radial segregation may be influenced by many factors, such as the convection"], curved solidification interfa~e[~-~]"), curved melting interface') and others. The influence of each factor is often interpreted by analytical solutions of simplified mode l~[ ' -~] " ) . However, the coupling process of more complete problems should be studied by the numerical method[59 61 .In this note, pure diffusion process is used to study the crystal growth process of binary alloy in the microgravity environment, and the influence of curved interfaces on solidification process in a cylindrical melting region with finite length and curved interfaces is investigated. The analytical solution was obtained by using the perturbation method and finite Hankel transform. The results show that the influence of curved melting interface on the radial segregation is smaller than that of curved solidification interface in general.Considering a melting region of radius a and length 1, the origin of the cylindrical coordinate system is located at the center of solidification interface and the z-axis is directed to the melting interface as shown in fig. 1. The equations and boundary conditions may be written as[2-41.
1)C ( r , x ) = C l ( r ) , z = W m ( r ) , (5 where C and CI are the concentrations in the melt and at the melting boundary respectively, V, D and k are the growth velocity, diffusion coefficient and effective segregation coefficient respectively, Ws( r ) and Wm( r ) are the functions of solidification interface and melting interface. In most cases, the studies have been completed for a plane melting interface Wm( r ) = 1) Xiong, B., Hu, W . R . , Crystal growth in floating zone with phase change and thermosolutal converction.