Microstructure and creep properties of a cast intermetallic Ti-46Al-2W-0.5Si alloy for gas turbine applications

被引：60

作者：

Lapin, J

Nazmy, M

机构：

[1] Slovak Acad Sci, Inst Mat & Machine Mech, Bratislava 83102, Slovakia

[2] ALSTOM Ltd, Dept Mat Technol, TGTMD, CH-5401 Baden, Switzerland

来源：

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 2004年 / 380卷 / 1-2期

关键词：

titanium aluminides; TiAl; creep; creep fracture; microstructure;

D O I：

10.1016/j.msea.2004.05.011

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

The microstructure and creep properties including minimum creep rate, time to 1% creep deformation and creep fracture time of a cast TiAl-based alloy with nominal chemical composition Ti-46Al-2W-0.5Si (at.%) were investigated. The creep specimens were prepared from investment-cast plate and two large turbine blades. Constant load creep tests were performed in air at applied stresses ranging from 150 to 400 MPa in the temperature range 973-1073 K. The microstructure of the specimens is characterised by optical, scanning and transmission electron microscopy before and after creep deformation. The minimum creep rate is found to depend strongly on the applied stress and temperature. The power law stress exponent of minimum creep rate is n = 7.3 and the apparent activation energy for creep is Q(a) = 427 +/- 14 kJ/mol. The initial microstructure of the creep specimen is unstable. The alpha(2)(Ti3Al)-phase transforms to gamma(TiAl)-phase and needle-like B2-precipitates during long-term creep testing at all testing temperatures. At lower applied stresses, the creep specimens fail by the growth and coalescence of cavities and small cracks formed along the gamma/alpha(2) interfaces. At the highest applied stresses, the specimens fail by nucleation and propagation of cracks. (C) 2004 Elsevier B.V. All rights reserved.

引用

页码：298 / 307

页数：10

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