目的 提高Nb-TiAl 合金的抗高温氧化性能。方法 采用NaF 为催化剂、1080 ℃下Si-Y 扩散共渗5 h 的方法，在高Nb-TiAl 表面制备了Y 改性硅化物渗层，利用SEM、EDS 和XRD 分析了渗剂中Y2O3 含量对共渗层组织及相组成的影响。结果 采用不同含量Y2O3 所制备的Si-Y 共渗层具有多层复合结构，共渗层的厚度随Y 元素的添加呈先增大后减小的趋势，共渗层的内层均由γ-TiAl 相组成；当渗剂中Y2O3 含量为2%和3%(质量分数)时，共渗层的外层主要为(Ti, Nb)Si2 相，中间层分为上下两层，分别为(Ti, Nb)5Si4 相和(Ti, Nb)5Si3 相，其中2% Y2O3 的Si-Y 共渗层有一层富Al 的(Ti, Nb)5Si4 和(Ti,Nb)5Si3 相组成的浅表层；当渗剂中Y2O3 含量为0%、1%和5%时，共渗层外层以(Ti, Nb)5Si4 相为主，中间层主要为(Ti, Nb)5Si3 相。结论 稀土Y 元素质量分数为2%~3%时具有明显的促渗作用，且获得的Si-Y 渗层组织结构致密，但添加过量的稀土元素会抑制Si 元素的吸附与扩散，使得Si-Y 共渗层中产生较多的孔洞，同时渗层的组织结构发生了改变。

The work aims to improve high temperature oxidation resistance of Nb-TiAl alloy. In this paper, Y modified silicide coating was prepared on high Nb-TiAl surface by taking NaF as catalyst and diffusing and co-penetrating Si-Y for 5 h under 1080 ℃. Effects of Y2O3 content in permeating agent on co-deposition coating and its phase composition were analyzed by virtue of XRD, SEM and EDS. All Si-Y coatings prepared with different contents of Y2O3 were provided with a multi-layer composite structure. Thickness of the coatings firstly increased and then decreased with the addition of Y element in the pack. All inlayers of the coatings were mainly composed of a γ-TiAl phase. The outer layers of the coatings prepared at 1080 ℃ for 5 h with the pack mixture containing 2% or 3% Y2O3 were mainly composed of (Ti，Nb)Si2 phase, and the middle layer was divided into upper and lower layers composing of (Ti, X)5Si4 and (Ti, X)5Si3 respectively. Moreover, a superficial layer consisting of Al-rich (Ti,Nb)5Si4 and (Ti,Nb)5Si3 was detected in the coating prepared with 2% Y2O3. However, the constituent phase turned to (Ti, Nb)5Si4 in the out layer and (Ti, X)5Si3 in the middle layer of the co-deposition coating when the pack mixture contained 0%, 1% or 5% Y2O3. The coating growth can be catalyzed obviously when the content of Y2O3 in the pack mixtures ranges between 2%~3%. However, excess addition of rare earth element will restrain the adsorption and diffusion of Si element, and thus a number of holes will appear on Si-Y co-deposition coating and the layer structure will change.