Effects of lamellar spacing, volume fraction and grain size on creep strength of fully lamellar TiAl alloys

被引:162
作者
Maruyama, K [1 ]
Yamamoto, R
Nakakuki, H
Fujitsuna, N
机构
[1] Tohoku Univ, Sch Engn, Dept Mat Sci, Sendai, Miyagi 98077, Japan
[2] Kobe Steel, Mat Res Labs, Kobe, Hyogo 65122, Japan
来源
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 1997年 / 240卷
基金
日本学术振兴会;
关键词
titanium aluminide; high temperature; creep deformation; creep rate; dislocation substructure; lamellar structure; lamellar spacing; grain size; alloy design;
D O I
10.1016/S0921-5093(97)00612-6
中图分类号
TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
Lamellar spacing, volume fraction of constituent phases and grain size are the major structural factors to be controled in alloy design of fully lamellar TiAl alloys. Creep tests were carried out on binary TiAl alloys with fully lamellar structure, to elucidate effects of the three structural factors on their creep strength. Lamellar alloys give better creep strength than the constituent single phases at higher stresses, due to their higher yield stress. Creep rate of lamellar alloys decreases with decreasing lamellar spacing, suggesting that a fine lamellar structure is effective in improving creep strength. The decrease is remarkable at high stresses. At low stresses however, the difference in creep rate diminishes, due to the increasing contribution of dynamic recrystallization and interface sliding. Creep rate is insensitive to volume fraction of the constituent phases and aluminum concentration is free in alloy design of TiAl alloys as far as creep strength is concerned. Creep rate is also independent of grain size d when d>100 mu m. Because of easy dynamic recrystallization in the lamellar alloys, creep rate may increase when d<100 mu m. If grain size <100 mu m is necessary for adequate ductility, dynamic recrystallization should be prevented by some means. (C) 1997 Elsevier Science S.A.
引用
收藏
页码:419 / 428
页数:10
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