Effect of thermal history on the superplastic expansion of argon-filled pores in titanium: Part II modeling of kinetics

N. G.D. Murray, D. C. Dunand*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Metals can be foamed to ca. 50% porosity in the solid state by the creation of gas-pressurized pores within the metal, followed by expansion of these pores at elevated temperatures. We present here models for the time-dependence of pore expansion during solid-state foaming performed under isothermal conditions, where the metal deforms by creep, and under thermal cycling conditions, where superplasticity is an additional deformation mechanism. First, a continuum-mechanics model based on the creep expansion of a pressure vessel provides good quantitative agreement with experimental data of isothermal foaming of titanium, and qualitative trends for the case of foaming under thermal cycling conditions. Second, an axisymmetric finite-element model provides predictions very similar to those of the pressure-vessel model, indicating that stress-field overlap is unimportant when pores are equidistant. Numerical modeling shows that stress-field overlap increases foaming rate when pores are clustered, and also cause anisotropic pore growth. However, a bimodal distribution of pore size was found to have little effect on pore growth kinetics.

Original languageEnglish (US)
Pages (from-to)2279-2291
Number of pages13
JournalActa Materialia
Volume52
Issue number8
DOIs
StatePublished - May 3 2004

Keywords

  • Creep
  • Foams
  • Metals
  • Porosity
  • Transformation superplasticity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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