Effect of Superplastic Deformation on Thermal Expansion Behavior of Tetragonal Zirconia Polycrystals

Abstract

Three mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) were superplastically deformed under various conditions and microstructural evolution was characterized. Thermal expansion properties of the 3Y-TZP specimens were then measured by a push-rod type dilatometer in a temperature range from 300 K to 1473 K. Experimental results showed that the mean coefficient of linear thermal expansion, , decreased with an increase in the volume fraction of cavities. The cavity dependence of value was dependent on temperature and was weakened with an increase in temperature. Changes in the average grain size and grain aspect ratio due to the superplastic deformations were found to have little effect on the thermal expansion property within the present experimental range.

Microstructural design of cellular 3 YTZ-Al2O3 ceramic membranes

“…However, the effects of alumina are consistent with known evidence of similar effects on phase transformation of TZP-based biomaterials [26], which were interpreted by considering thermal expansion mismatch between TZP and corundum. For TZP one expects an average value of linear thermal expansion coefficient S NZ[ ≈ 11.5 10 _ ` from temperature up to 1573 K or above [27], whereas for corundum one may assume an average value S ≈ 9 10 _ ` [28]; this causes volumetric mismatch (ε V ) for a corundum particle in a surrounding TZP matrix, on cooling from firing temperatures to room temperature:…”

A Simple Method to Improve Superplastic Elongation and Strength of 3Y-TZP Deformed at High Strain-Rates

“…They are lying along grain boundaries that are nearly normal to the tensile direction. Now, a result of thermal expansion measurements has suggested [12] that an average width of the gaps each flat cavity has is within a few nanometers. In the course of the thermal expansion measurements, we have found [12] that the gaps the flat cavities have were reduced and/or even closed when specimens were heated up to 1473K.…”

“…Now, a result of thermal expansion measurements has suggested [12] that an average width of the gaps each flat cavity has is within a few nanometers. In the course of the thermal expansion measurements, we have found [12] that the gaps the flat cavities have were reduced and/or even closed when specimens were heated up to 1473K. This experimental result implies that if superplastic deformation is interrupted, i.e., the cross-head movement is reversed and accordingly the applied load is removed, and then the specimen is kept at the superplastic deformation temperature or above that temperature for some time, almost all of the flat cavities may be reduced or closed.…”

Superplasticity and Superplastic Diffusion Bonding of a Fine-Grained TiAl Alloy

“…6) The superplastic behavior and deformation mechanisms of various alloys have been extensively studied, [7][8][9][10][11][12][13] and the superplastic behavior of TiAl-based alloys has been demonstrated in the past few years. [14][15][16][17] Significant superplastic flow requires a fine, randomly distributed equiaxed grain microstructure, with grain size in the range of 1-10 mm.…”