Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-24T17:01:17.702Z Has data issue: false hasContentIssue false
  • English
  • Français

Hot extrusion of nanocrystalline yttria-stabilized tetragonal zirconia polycrystals

Published online by Cambridge University Press:  25 October 2016

Tatsuo Kumagai
Tatsuo Kumagai*
Affiliation:
Department of Mechanical Engineering, School of Systems Engineering, National Defense Academy, Yokosuka-shi, Kanagawa 239-8686, Japan
*
a)Address all correspondence to this author. e-mail: [email protected]
Get access

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 (v0) shows a sharp maximum, followed by a continuous decrease until it reaches a steady-state v0 value. Visual observations of the material flow by using graphite foil markers indicate that the deformation zone at the steady-state v0 is well represented by a spherical velocity field. The decrease in v0 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 v0 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.

Keywords

extrusionceramicstress/strain relationship
Type
Articles
Information
Journal of Materials Research , Volume 31 , Issue 21 , 14 November 2016 , pp. 3290 - 3302
Check for updates
Copyright
Copyright © Materials Research Society 2016 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

Contributing Editor: Yanchun Zhou

References

REFERENCES

Kumagai, T.: Rapid densification of yttria-stabilized tetragonal zirconia by electric current-activated/assisted aintering technique. J. Am. Ceram. Soc. 94, 1215 (2011).CrossRefGoogle Scholar
Krell, A., Blank, P., Ma, H., and Hutzler, T.: Transparent sintered corundum with high hardness and strength. J. Am. Ceram. Soc. 86, 12 (2003).Google Scholar
Kellett, B.J.: High temperature extrusion behavior of fine-grain ZrO2 . J. Mater. Res. 5, 2165 (1990).Google Scholar
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).CrossRefGoogle Scholar
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).CrossRefGoogle Scholar
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).Google Scholar
Balasubramanian, N. and Langdon, T.G.: Comment on the role of intragranular dislocations in superplastic yttria-stabilized zirconia. Scr. Mater. 48, 599 (2003).Google Scholar
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).Google Scholar
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).CrossRefGoogle Scholar
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.Google Scholar