Aerospace engine and airframe designers are constantly seeking lighter weight high strength materials to reduce weight and improve performance of powerplants and aircraft. Titanium metal matrix composites (Ti MMCs) have offered the promise of significant weight savings since their initial development in the early 1960s but until recently, their inadequate quality and reproducibility combined with high processing and materials costs have prevented their introduction into production applications.This paper describes the state-of-the-art for Ti MMC aerospace fabrications, their potential payoffs and the recent advances in processing which are now leading to high quality, affordable Ti MMC components.

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Residual stresses induced during unlubricated sliding contact have been measured by the two-exposure technique as well as by peak shift analysis. The peak shift analysis provides the necessary information for the determination of the sum of the principal residual stresses and stacking fault probability. The results of the lattice parameter method suggested by Wagner are compared with those obtained via the conventional two-exposure X-ray technique. If the 222 and 400 reflections are of sufficient intensity, either method may be used to determine the state of stress. However, if the peaks are very diffuse because of strain hardening, the two-exposure technique yields the most reliable results.