Monotectic Crystallization of Melts in the ZrO_2-Al_2O_3 System

摘要

The morphology of the crystalline phases prepared at different cooling rates,temperatures,and compositions of melts in the ZrO_2-Al_2O_3 system is investigated.It is established that both the quenched and slowly crystallized samples containing 35-70 wt % ZrO_2 have a submicron structure.Outside this concentration range,the ingots have a zonal structure:the peripheral region is formed by large baddeleyite crystals(at a ZrO_2 content higher than 70 wt %)or corundum crystals(at a ZrO_2 content lower than 30 wt %).This character of the crystallization confirms the presence of the phase separation(liquid immiscibility)region in melts of this system.A variant is proposed for the phase diagram of the system under investigation.