论文部分内容阅读
采用Si-Al-Y_2O_3包埋共渗工艺在Nb-Ti-Si基超高温合金表面制备Y改性的Si-Al共渗层,分析了渗剂中Al粉含量对渗层组织和相组成的影响,并研究了其在1250℃的抗氧化性能.结果表明:采用不同Al粉含量的渗剂在1050℃所制备的Si-Al-Y_2O_3共渗层均具有多层复合结构,且渗层的内层都是由Al_3(Nb,X)(X代表Ti,Cr和Hf)和(Cr,Al)_2(Nb,Ti)相组成;当渗剂中Al粉含量为10%(质量分数)时,渗层的外层以(Nb,X)Si_2相为主,中间层以(Nb,X)_5Si_3相为主;当渗剂中Al粉含量为15%时,渗层中间层由(Nb,X)_5Si_3及Al_3(Nb,X)两相组成,而外层组成相相对于渗剂中Al粉含量为10%时的未发生变化;当渗剂中Al粉含量为20%时,渗层的外层以(Nb,X)_3Si_5Al_2相为主,(Nb,X)Si_2相弥散分布其中,中间层则以Al_3(Nb,X)为基体相,(Nb,X)_5Si_3相弥散分布其中,并在其上部分布较少而下部较密集.Y在渗层中的分布不均匀,并且随着渗剂中Al粉含量的提高,渗层各层中的Y含量均增加.Si-Al-Y_2O_3共渗层的形成是一个在合金表面先沉积Al、后沉积Si的有序过程,其生长服从抛物线规律.在1250℃下氧化5 h后,渗层表面生成了致密的Al_2O_3膜.
Y-modified Si-Al co-diffusion layer was prepared on the surface of Nb-Ti-Si-based superalloy by Si-Al-Y_2O_3 embedding technique. The effect of Al powder content in the penetration agent on the microstructure and phase composition And the oxidation resistance of the Si-Al-Y_2O_3 composite coatings was investigated at 1250 ℃ .The results show that all of the Si-Al-Y_2O_3 permeation layers prepared at 1050 ℃ have multi-layer composite structure with different Al powder content, The inner layers are composed of Al 3 (Nb, X) (X stands for Ti, Cr and Hf) and (Cr, Al) _2 (Nb and Ti) phases. When the content of Al powder in infiltrant is 10% (mass fraction) (Nb, X) Si 2 phase is dominant in the outer layer and (Nb, X) 5 Si 3 phase is dominant in the outer layer. When the content of Al powder in the penetration agent is 15% X) _5Si_3 and Al_3 (Nb, X), while the composition of the outer layer did not change when the content of Al powder in the penetration agent was 10%. When the content of Al powder in the penetration agent was 20% (Nb, X) _3Si_5Al_2 phase, the (Nb, X) Si_2 phase is dispersed in the outer layer, while the intermediate layer is dispersed in the matrix phase of Al_3 (Nb, X) And its distribution in the upper part of less dense and the lower part of the dense distribution of Y in the infiltration layer, and with the infiltration of Al powder content, infiltration The content of Y in each layer increases.The formation of Si-Al-Y_2O_3 co-diffusion layer is an orderly process of depositing Al and then depositing Si on the surface of the alloy, and the growth follows the parabolic law and is oxidized at 1250 ℃ for 5 h After that, a dense Al 2 O 3 film was formed on the surface of the layer.