Influence of notch shape and geometry during creep crack growth testing ofTiAl intermetallic compounds

In order to establish the optimum pre-crack shape and geometry for creep cr ack growth (CCG) testing of high-temperature brittle materials, several sha pes of starter notches were evaluated experimentally on TiAl intermetallic compound. Fatigue pre-cracks are frequently inappropriate in these material s because they tend to promote out-of-plane crack growth in the lamellar st ructured TiAl materials. Based on the experimental results with several not ch shapes and also an analytic assessment of stress distribution around not ch-tip, a V-notched specimen is proposed as being optimum for generating cr eep crack growth data in lamellar structured TiAl. A procedure for machinin g the notches to minimize its effect on the CCG behavior is also outlined. (C) 1998 Elsevier Science Ltd. All rights reserved.