ROLE OF Y DURING HIGH-TEMPERATURE OXIDATION OF AN M-CR-AL-Y COATING ON AN NI-BASE SUPERALLOY

被引:55
作者
TAWANCY, HM [1 ]
ABBAS, NM [1 ]
BENNETT, A [1 ]
机构
[1] ROLLS ROYCE PLC,DERBY DE24 8BJ,ENGLAND
关键词
D O I
10.1016/0257-8972(94)90130-9
中图分类号
TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
A study was carried out to determine the role of Y during high temperature oxidation or an M-Cr-Al-Y-type coating on an Ni-base superalloy using various techniques of electron microscopy. Prior to oxidation exposures, Y was found to segregate within an external surface layer of the coating about 5 Irm in thickness as well as within the interdiffusion zone. After exposure at 1000 or 1100 degrees C in still air, Y exhibited a preferential tendency for segregation at grain boundaries of alpha-Al2O3 scale developed by the coating, however, a finite concentration of Y was also present in solid solution. In addition, some of the Y was found to oxidize into a Y-rich oxide ''pegs'' within the alpha-Al2O3 scale and extending into the coating. Experimental results showed that segregation of Y to grain boundaries could maintain a fine-grained scale after exposure for up to 1000 h at 1000 or 1100 degrees C. It was concluded that, for the coating-substrate system studied, Y could improve the protective nature of alpha-Al2O3 scale by various mechanisms operating simultaneously.
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收藏
页码:10 / 16
页数:7
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