Skip to main content Accessibility help
×
Home

Hot extrusion of nanocrystalline yttria-stabilized tetragonal zirconia polycrystals

  • Tatsuo Kumagai (a1)

Abstract

Hot indirect extrusion behaviors of fully dense 3 mol% Y2O3-stabilized ZrO2 polycrystals with a grain size of 80 nm were investigated by using a conical graphite die. During early extrusion at 1843 K and a constant compression stress of 60–80 MPa, the relative moving billet velocity (v 0) shows a sharp maximum, followed by a continuous decrease until it reaches a steady-state v 0 value. Visual observations of the material flow by using graphite foil markers indicate that the deformation zone at the steady-state v 0 is well represented by a spherical velocity field. The decrease in v 0 corresponds to the transition from heterogeneous to homogeneous deformation. The stress exponent (n) of 2.07 was obtained from the log–log plots of the steady-state v 0 versus the external applied stress that is compensated by threshold and sliding friction stresses. This n value suggests plastic deformation through grain-boundary sliding in indirect extrusion.

Copyright

Corresponding author

a) Address all correspondence to this author. e-mail: kumagai@nda.ac.jp

Footnotes

Hide All

Contributing Editor: Yanchun Zhou

Footnotes

References

Hide All
1. Kumagai, T.: Rapid densification of yttria-stabilized tetragonal zirconia by electric current-activated/assisted aintering technique. J. Am. Ceram. Soc. 94, 1215 (2011).
2. Krell, A., Blank, P., Ma, H., and Hutzler, T.: Transparent sintered corundum with high hardness and strength. J. Am. Ceram. Soc. 86, 12 (2003).
3. Kellett, B.J.: High temperature extrusion behavior of fine-grain ZrO2 . J. Mater. Res. 5, 2165 (1990).
4. Melendo, M.J. and Rodríguez, A.D.: High temperature mechanical characteristics of superplastic yttria-stabilized zirconia. An examination of the flow process. Acta Mater. 48, 3201 (2000).
5. Retamal, C., Lagos, M., Moshtaghioun, B.M., Cumbrera, F.L., Rodríguez, A.D., and García, D.G.: A new approach to the grain-size dependent transition of stress exponents in yttria tetragonal zirconia polycrystals. The theoretical limit for superplasticity in ceramics. Ceram. Int. 42, 4918 (2016).
6. García, D.G., Martín, C.L., Bernabé, A.M., and Rodríguez, A.D.: Correlation between yttrium segregation at the grain boundaries and the threshold stress for plasticity in yttria stabilized tetragonal zirconia polycrystals. Philos. Mag. 83, 93 (2003).
7. Balasubramanian, N. and Langdon, T.G.: Comment on the role of intragranular dislocations in superplastic yttria-stabilized zirconia. Scr. Mater. 48, 599 (2003).
8. Mora, F.G., García, D.G., Melendo, M.J., and Rodríguez, A.D.: Experimental assessment of plasticity of nanocrystalline 1.7 mol% yttria tetragonal zirconia polycrystals. J. Am. Ceram. Soc. 88, 1529 (2005).
9. Matsui, K., Yoshida, H., and Ikuhara, Y.: Grain-boundary structure and microstructure development mechanism in 2–8 mol% yttria-stabilized zirconia polycrystals. Acta Mater. 56, 1315 (2008).
10. Avitzur, B.: Metal Forming: Processes and Analysis, McGraw-Hill Series in Materials Science and Engineering (McGraw-Hill Book Company, New York, USA, 1968); p. 500.

Keywords

Hot extrusion of nanocrystalline yttria-stabilized tetragonal zirconia polycrystals

  • Tatsuo Kumagai (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed