An Examination of the Thermally Related Factors Influencing the Melting/Dissolution of Solids in Liquid Titanium

Abstract

The melting/dissolution behaviour of a solid in liquid titanium has been investigated with the aid of an Electron Beam Button Furnace (EBBF) to understand the phenomena contributing to the melting/dissolution of exogenous solids introduced into liquid titanium during melt processing and casting. To begin, cylindrical rods of commercial purity (CP) titanium were dipped into a molten CP titanium pool for various periods of time to investigate the melting/dissolution behaviour in the absence of compositional effects. The dimensions of the dipped rods were measured before and after various immersion times allowing quantification of the evolution of the solid/liquid interface and melting rate. The temperature within the dipped rod was also measured during melting to provide additional quantitative data on heat transport for analysis. The results show that the molten titanium initially solidifies onto the cold rod. The solid/solid interface formed between the rod and solidified titanium was found to significantly reduce the heat transfer to the rod. After a short period of time, the solidified titanium re-melts followed by melting and dissolution of the rod. Analysis with the model has confirmed that both thermally induced buoyancy and, in particular, thermally induced Marangoni forces contribute significantly to the melting/dissolution process. A numerical model has been developed to describe the solidification and melting process, the results of which are shown to correlate well with experimentally obtained data.