Crystallization Behaviour of the Si-Al-Zr-O Amorphous Bulk

The in situ controlled crystallizing process of Si-Al-Zr-O(SAZ)amorphous bulk was investigated by DSC,XRD,SEM and TEM techniques.The amorphous undergoes structural changes by treating at different temperatures.Phase segregation occurs at about 900℃,resulting in the formation of Si-rich and A1,Zr-rich regions.The t-ZrO_2 is crystallized from the Al,Zr-rich region at 920-950℃followed by poorly defined Al-Si spinel.With the increase of temperature up to 1000℃,mullite forms by reaction between Al-Si spinel and amorphous silica.The main crystalline phases identified are t-ZrO_2, mullite and some cristobalite with the spinel disappearing above 1000℃.