ANALYTICAL STUDY OF THE CONDUCTIVE REGIME OF CONVECTION FLOWS IN MOLTEN ALLOY

We present an analytical study of the structure of the flow of a molte n alloy The alloy is contained in a cylindrical crucible and locally h eated on its free surface by an electron beam. Due to the high tempera ture under the electron beam, local evaporation of alloy components oc curs. The difference of volatility of the two components creates a con centration gradient in the melt. The study consists of determining ana lytically the structure of the flow with the following approximations: the aspect ratio height over diameter of the liquid layer is small an d for moderate heat supply We show that in the first significant order the flow pattern in the conductive regime is governed by two dimensio nless numbers, a Marangoni and a Rayleigh number that measure the rela tive strengths of the thermal and solutal effects. (C) Academie des Sc iences/Elsevier; Paris.