Formation of Intermediary Phases During Reactive Sintering Production of Ti-Al and Ti-Al-Si Alloys

摘要

Bulk intermediary phases of Ti-Al and Ti-Al-Si systems are promising materials for high temperature applications. However, their production by melt metallurgy is problematic due to high melting points of the intermediary phases and high reactivity of the melt. The reactive sintering powder metallurgy is a simple alternative to conventional melting processes. During this process, a pressed powder mixture of pure metals or other precursors is transformed into bulk intermediary phases by thermally activated in-situ reaction. During reactive sintering of Ti-Al-Si alloys, molten Al-Si alloy fills pores and reacts with titanium producing a mixture of titanium silicides and aluminides. In this work, kinetics and mechanism of the formation of intermediary phases in Ti-Al and Ti-Al-Si systems were described. Titanium was exposed to molten aluminium or Al-Si alloys with silicon content of 30 and 50 wt.%. Results were successfully applied to the preparation of low-porosity Ti-Al-Si alloys.