中文摘要：

通过1000～1150℃Si-Al包埋共渗8h的方法在铌基超高温合金表面制备Al改性硅化物抗氧化涂层,结果表明：实验温度下制备的涂层均具有多层复合结构；不同温度下共渗涂层外层的相组成不同,但最内层均由（Nb,Ti）Al3和（Cr,Al）2（Nb,Ti）组成。1050℃、8hSi-Al共渗在合金表面形成了Al改性的硅化物涂层,其最外层主要为Nb3Si5Al2,依次往内为（Nb,X）（Si,Al）2（X代表Ti,Cr和Hf元素）层、（Nb,X）5Si3层以及最内层；而在1000℃、8h条件下Si-Al共渗形成的涂层以（Nb,Ti）Al3为主,其中含有少量的（Nb,X）5Si3,没有形成以硅化物为主的涂层；在1100℃、8h和1150℃、8h条件下Si-Al共渗形成的涂层外层以（Nb,X）（Si,Al）2为主,但其中Al含量（摩尔分数）仅为2.35%,没有形成Nb-Si-Al三元化合物层。

英文摘要：

Al-modified silicide coatings on an advanced Nb-based ultrahigh temperature alloy were prepared by co-depositing Si and A1 at 1 000, 1 050, 1 100 and 1 150℃ for 8 h, respectively. The results show that the coatings obtained by these processes have a multiple layer structure. The outer layers of the coatings have the different phase constituents at different coating temperature, but all the innermost layers of the coatings are constitutive of （Nb,Ti）Al3 and （Cr,Al）2（Nb, Ti）. Al-modified （Nb,X）Si2（X represents Ti,Cr and Hf） coatings with an Nb3Si5Al2 outermost layer are obtained by co-depositing Si and A1 at 1 050℃ for 8 h. The coatings prepared at 1000 ℃ for 8 h are mainly constitutive of （Nb,Ti）Al3, and the coatings prepared at 1100℃ for 8 h and 1150℃for 8h are mainly constitutive of （Nb,X）-（Si,Al）2 with 2.35%Al（mole fraction）.