Accession Number : ADA189025

Title :   Elevated Temperature Crack Growth Studies of Advanced Titanium Aluminides.

Descriptive Note : Final rept. Sep 86-Apr 87,

Corporate Author : SYSTRAN CORP DAYTON OH

Personal Author(s) : Venkataraman, Srivathsan

PDF Url : ADA189025

Report Date : Sep 1987

Pagination or Media Count : 77

Abstract : Ordered intermetallic titanium aluminide Ti AL alloyed with niobium possesses attractive high temperature properties and moderate low temperature ductibility. Currently, its application is limited to static components in aircraft gas turbine engines. To extend their use to rotating components of turbine engines, better understanding of life limiting processes such as creep/fatigue crack growth and fracture is required. Phase I of this Air Force Small Business Innovative Research program involved investigation of fatigue crack growth in an alpha two titanium aluminide plus niobium alloy (titanium - 16 wt% aluminum - 10 wt% niobium) as a function of temperature and environment. Computer automated fatigue crack growth tests were conducted in both air and vacuum environments at temperatures ranging from room temperature to 1200 F (649 C). Two heat treatment conditions, namely, beta solution and alpha + beta solution resulted in coarse and fine grain materials, respectively, with varying alpha two morphology. Fractographic analyses were conducted for all test specimens.

Descriptors :   *CRACK PROPAGATION, *TITANIUM ALUMINIDE, AIR FORCE, AIRCRAFT ENGINES, ALUMINIDES, CREEP, FATIGUE(MECHANICS), FINE GRAINED MATERIALS, FRACTOGRAPHY, GAS TURBINES, HEAT TREATMENT, HIGH TEMPERATURE, LOW TEMPERATURE, MORPHOLOGY, NIOBIUM ALLOYS, NICKEL ALLOYS, COBALT ALLOYS, INTERMETALLIC COMPOUNDS, SUPERALLOYS

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE