(西北工業(yè)大學(xué) 凝固技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，西安 710072)
摘 要: 采用在1 250、1 350和1 400 ℃ Si-Cr包埋共滲10 h的方法，在Ti-Nb-Si基超高溫合金表面制備了Cr改性硅化物涂層。結(jié)果表明：各溫度下制備的涂層均具有多層復(fù)合結(jié)構(gòu)；隨包埋共滲溫度的升高，涂層外層和中間層的組成相都發(fā)生改變。經(jīng)1 250 ℃，10 h Si-Cr共滲時(shí)涂層外層為(Ti, X)5Si3(X代表Nb、Hf和Cr元素)，中間層為(Ti, X)5Si4，過渡層(Ti, X)5Si3很薄；當(dāng)提高共滲溫度至1 350 ℃時(shí)，涂層外層中Cr含量明顯提高，外層除了(Ti, X)5Si3外，還出現(xiàn)含Cr的三元相(Nb1.95Cr1.05)Cr2Si3，中間層由(Ti, X)5Si4和(Ti, X)5Si3兩相組成，而過渡層((Ti, X)5Si3)增厚；繼續(xù)提高共滲溫度至1 400 ℃時(shí)，涂層外層主要由(Nb1.95Cr1.05)Cr2Si3三元相組成，中間層已全部由(Ti, X)5Si3相組成，在過渡層與基體間還存在不連續(xù)的塊狀(Nb, Ti)3Si相，Si-Cr共滲溫度對Cr擴(kuò)散的影響更為顯著。
關(guān)鍵字: Ti-Nb-Si基超高溫合金；包埋滲；Si-Cr共滲；涂層結(jié)構(gòu)
（State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:The Cr-modified silicide coatings were prepared on Ti-Nb-Si based ultrahigh temperature alloy by Si-Cr co-deposition processes at 1 250, 1 350 and 1 400 ℃ for 10 h, respectively. The results show that the Si-Cr co-deposition coatings have multi layer structure. The phase constituents of outer layers and intermediate layers of the coatings change with increasing co-deposition temperatures. The outer layer and intermediate layer of the coating prepared at 1 250 ℃ for 10 h consist of (Ti, X)5Si3 (X represents Nb, Hf and Cr elements) and (Ti, X)5Si4, respectively. The transitional layer of this coating is very thin and composed of (Ti, X)5Si3. The content of Cr increases significantly in the outer layer of the coating prepared at 1 350 ℃ for 10 h, and (Nb1.95Cr1.05)Cr2Si3 ternary phase forms in this layer besides (Ti, X)5Si3 phase. The intermediate layer is composed of (Ti, X)5Si4 and (Ti, X)5Si3 phases, and the transitional layer composed of (Ti, X)5Si3 phase is thickened obviously. (Nb1.95Cr1.05)Cr2Si3 ternary phase is the single phase constituent in the outer layer of the coating prepared at 1 400 ℃ for 10 h, and the intermediate layer is composed of (Ti, X)5Si3 thoroughly. Discontinuous (Nb, Ti)3Si blocks are also found between the transitional layer and substrate. The influence of temperature on the diffusion ability of Cr atoms is greater than that of Si atoms in the Si-Cr co-deposition processes investigated.
Key words: Ti-Nb-Si based ultrahigh temperature alloy; pack cementation; Si-Cr co-deposition; coating structure
