900F Titanium Alloy Development.
Final rept. 1 Apr 69-1 Jun 70,
GENERAL ELECTRIC CO CINCINNATI OH MATERIAL AND PROCESS TECHNOLOGY LABS
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Twelve alloys were initially evaluated through a Phase 1 screening study with respect to the tensile properties, creep strength and metallurgical stability. The conclusion of Phase 1 was the selection of the C1 alloy Ti-4.5A1-2Sn-3Zr-3Ga-1Mo-0.5Si for further study and the design of a thirteenth alloy, Ti77 Ti-6.5A1-4Zr-1.5Mo-0.7Si, for a Phase 1 type screening evaluation. The Ti77 alloy composition was selected based on the results of Phase I. The Phase 2 results demonstrated the creep resistance for both C1 and Ti77 was superior to the present commercial alloys. However, both alloys exhibit metallurgical instability as shown by ductility and toughness losses and require further evaluation. The kinetics of the toughness degradation phenomenon indicate the formation of the Ti3X XA1, Ga, Sn phase is responsible for metallurgical instability. The creep resistance of the C1 alloy, and presumably the Ti77 alloy, is hypothesized to be derived from dispersion type strengthening by the Ti3X phase in the alpha titanium matrix and by pinning of two phases were identified by thin foil electron diffraction techniques in these respective locations. Author
- Metallurgy and Metallography
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