PHASE RELATIONSHIPS OF O'-β' IN Y-Si-AI-O-N SYSTEM

Sub-solidus phase relationships of SiNO-AlN-YOsystem have been studied and phase relationships concerning O’-β’ in Y-Si-Al-O-N system revised. In si-Al-O-N system there should be a tie line between SiNand O’（x=0.3）, thus dividing the 2-phase region of 0’-β’ into two compatibility triangles SiN-SiNO-O’（x=0.3） and SiN-β’（z=0.8）-O’（x=0.3）. At 1550℃, SiN-O’（x=0.3）-YAG-H-phase forms a compatible region. If it is heated up to 1700℃ and annealed at 1200—1300℃, H-phase decomposes and the compatible region becomes SiN-O’（X=0.3）-YAG-YSiO. The phase relationships suggested are SiN-SiNO-O’（X=0.3）-YSiO（or H）, SiN-O’（x=0.3）-YAG-YSiO（or H） and SiN-β’（z=0.8）-O’（x=0.3）-YAG. The establishment of the phase relationships has significant bearing on the fabrication of O’-β’ composite ceramics.