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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.

Alloy 718 forgings have been used extensively in gas turbines for aircraft engines for decades. However their application to land-based power generation gas turbines has been limited to the size of the forgings which can be produced by available forging equipment. GE's recently developed heavy duty gas turbines now require forgings which must be produced from 915 mm diameter ingots which exceed 15,000 kg. The initial hurdle was to melt these large ingots successfully without segregation defects. This was achieved and the results were discussed in a previous conference. This paper describes the unique challenges to converting these ingots into the largest Alloy 718 forgings ever produced. The development work associated with processing these ingots into a uniform fine grain microstructure with the required mechanical properties will be described. The importance of process modeling for developing a process to achieve the structure and property goals will also be discussed.

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