Interfacial Reaction between Liquid Titanium and Oxide Mold Contained Alpha-case Formation Phase during Investment Casting

摘要

Investment casting could produce a greatly complex component with a low manufacturing cost For some titanium alloys which are difficult to shape by plastic deformation process, such as forging and machining, they could be easily used in investment casting process. However, liquid titanium is extremely reactive to ceramic molds, resulting in alpha-case at the casting-mold interface. Alpha-case well known as a layer enriched oxygen and metallic element, leads to a deterioration of mechanical properties, therefore, has to be removed by chemical milling or machining. However, these processes are wasteful and inefficient, and the casting products lose its dimensional tolerances. The aim of this study is to suppress the interfacial reaction between titanium melts and oxide mold by addition of alpha-case formation phase on the mold before casting. Alpha-case formation phase in the mold side was either induced during the firing process or added to the slurry. Plasma arc apparatus was used for melting of titanium alloys.