Interphase behavior of titanium matrix composites at elevated temperature

This paper examines the effect of temperature and thermal exposure on the i nterphase behavior of continuous fiber reinforced titanium metal matrix com posites. The system considered is SCS-6/Timetal-21S, Elevated temperature f iber push-out tests were conducted to determine the effect of rest temperat ure on interphase shear properties. Corresponding variations of debonding s heer strength and frictional shear stress with test temperature are present ed acid discussed. Thermal exposure. both in a vacuum and an air environmen t, has been conducted on specimens, with temperatures up to 650 degreesC an d exposure times of up to 100 h. The resulting size and composition of the interphase have been examined. Fiber push-out tests were carried out at roo m and elevated temperature on the aged specimens. Results are discussed in terms of the influence of relaxation and oxidation on the debond shear stre ngth. Using the experimentally determined interphase sheer properties. the interphase toughness has been calculated and discussed in relation to inter face decohesion models. (C) 2001 Elsevier Science Ltd. All rights reserved.