Superplastic foaming of titanium and Ti-6Al-4V
- Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
- Swiss Federal Inst. of Tech., Zuerich (Switzerland). Dept. of Materials
Solid-state foaming of metals can be achieved by hot-isostatic pressing of powders in presence of argon followed by expansion of the resulting high-pressure argon bubbles at ambient pressure and elevated temperature. This foaming technique was first demonstrated by Kearns et al. for Ti-6Al-4V, but is limited by its low creep rate and ductility, which lead to early cell wall fracture. The authors address these issues by performing the foaming step under superplastic conditions. Rather than using microstructural superplasticity (requiring fine grains which are difficult to achieve in porous powder-metallurgy materials), they used transformation superplasticity, which occurs at all grain sizes by biasing with a deviatoric stress (from the pore pressure) of internal stresses (from the allotropic mismatch during thermal cycling about the allotropic temperature range). As compared to control experiments performed under isothermal creep conditions, superplastic foaming under temperature cycling of unalloyed titanium and alloyed Ti-6Al-4V led to a significantly higher pore volume fraction and higher foaming rate.
- OSTI ID:
- 361825
- Report Number(s):
- CONF-980405-; TRN: IM9933%%207
- Resource Relation:
- Conference: Spring meeting of the Materials Research Society, San Francisco, CA (United States), 13-17 Apr 1998; Other Information: PBD: 1998; Related Information: Is Part Of Porous and cellular materials for structural applications; Schwartz, D.S.; Shih, D.S. [eds.] [Boeing Co., St. Louis, MO (United States)]; Evans, A.G. [ed.] [Harvard Univ., Cambridge, MA (United States)]; Wadley, H.N.G. [ed.] [Univ. of Virginia, Charlottesville, VA (United States)]; PB: 337 p.; Materials Research Society symposium proceedings, Volume 521
- Country of Publication:
- United States
- Language:
- English
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