通过恒定横梁速度和恒定载荷压缩试验，对超塑性3mol％Y2O3稳定四方ZrO2多晶体的压缩塑性形变进行了研究．测定了平均晶粒尺寸从0．30～1．33μm的3Y－TZP材料的塑性流动应力，应力指数和蠕交活化能；用扫描和透射电镜观察了试样的显微结构．结果表明，3Y－TZP材料塑性形变的机理为扩散适应的晶界滑移．随着晶粒尺寸由0．30μm增大至1.33μm，应力指数从3．2减小至1．4，活化能从580kJ／mol减小至500kJ／mol．形变机理随晶粒大小发生变化．对于晶粒较粗的3Y－TZP材料，当应变速率较高时，形变过程中在材料内产生晶间孔穴．
The compressive plastic deformation of superplastic 3 mol% yttria-stabilized zirconia polycrystalswith different grain sizes was studied by both constant cross head speed and constant load tests incompression in air. The superplastic-like phenomenon in 3Y-TZP was exhibited. The grain shape remainedequiaxed and the grains were dislocation-free after deformation. It indicated that the deformationmechanism was grain boundary sliding accommodated by diffusion. The flow stress decreased markedly with theincrease of the strain rate and grain size and with the decrease of the temperature. The stress exponent and activation energy for creep decreased from 3.2 to 1.4 and from 580jK/mol to 500kJ/mol with the increment of the grain size from 0.30μm to 1.33μm, respectively. That the change in the stress exponent and activation energy implied the change in deformation mechanism with the grain size. Cavitation occurred at triple junctions in the materials with coarser grain sizes during deformation at high strain rates and a part of the cavities developed along grain boundaries and linked as crack-like cavities.
参考文献
| [1] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%