rature. 2.3 Microstructure Features of SisNa with AZ-Type Non-Oxide Additive Superior RT and HT mechanical properties and oxidation behavior of ZAN are closely related to the microstructures.Hexagonal of elongated B/-SS grains of <1um are showh in specimen hot pressed at 1800C under.TEM,Many ZrN particles dispersed in matrix and secondary crystalline phase distributed in triple regions of grain boundaries are observed.(Fig.4,5) Fig.4 TEM of ZAN showing secondary crystalline phase in triple regions. (a)ZrN particles dispersed in matrix (b)EDX analysis of the compositions of secondary crystalline phase:atom ratio of Zr/Si=1/3 Fig.5 Intergranular glassy phase in the triple regions of Be-SiaN4 matrix Zr and Si are identified in this crystalline phase with EDX which might be oxynitrides of.Si and Zr precipitated from liquid phase during cooling after hot-pressing. Minor intergranular glassy phase is observed at few triple regions,but is not found in most of grain boundaries as shown in lattice images in Fig.6. In specimens ZAN hot-pressed at 1650C,different superlattice structures in 39火 蓄 一 一 介 父 声 ‘ 一 卜 ℃ 兮 ， 井 宜。 呈 台 么 沈 刀， 一 一 介 一 。 。 ， 七 一 。 不 一 ℃ ， “ 冬孕