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Effect of the Strength of the Parent Phase on the DrivingForce for the Martensitic Transformation of Partially Stabilized Zirconia

母相强度对部分稳定氧化锆马氏体相变驱动力的影响

基本信息

批准号：
06650728
负责人：
HAYAKAWA Motozo
金额：
$ 1.28万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

1. The effect of the composition and the grain size on the strength of the parent phaseTZP (Tetragonal Zirconia Polycrystals) specimens were prepared with five different composition, namely 3Y,0.75Y-3Ce, 1.5Y-6Ce, 2.25Y-9Ce, and 12Ce, where Y and Ce denote mol% of Y_2O_3 and CeO_2 in zirconia, respectively. The grain size of the specimens was modified by post sinter annealing.The strength of the tetragonal phase as measured by Vickers hardness tester decreased monotonically with increasing ceria content (or decreasing yttria content), but the rate of the decrease became increasingly steep with increasing ceria content. The grain size dependence was reasonably well approximated by the Hall-Petch relation. Thus, the hardness of the two extreme compositions was represented by the following empirical equations :Hv=1250-0.90 (T-293) +100 (d^<-0.5>-1.21) for 3y-TZPHv= 950-0.68 (T-293) +430 (d^<-0.5>-0.72) for 12Ce-TZPwhere T denote temperature in K and d grain size in micrometer.2. The effect of the composition on the transformation temperatureThe specimens used in the above experiment did not transform by cooling as low as liquid nitrogen temperature except a few. Thus, specimens with lower yttria content were prepared for the Ms and As temperature measurement. These temperatures were represented by the follwing equations :As=1459-269Y for0<Y<3Ms=1279-364Y for0<Y<1.5Since the Ms of 2Y was below 77K,the driving force as measured by As-Ms rapidly increased when Y content exceeds 2mol%. This is unlikely to be explained by the free energy change or hardness increase with the increasing Y content. A further study is necessary to explain this drastic change of Ms temperature.

1.组成和粒度对母体相强度的影响用五种不同的成分，即3Y、0.75Y-3Ce、1.5Y-6Ce、2.25Y-9Ce和12Ce制备了TZP(四方氧化锆多晶)样品，其中Y和Ce分别表示氧化锆中Y_2O_3和CeO_2的摩尔分数。维氏硬度计测得的四方相强度随CeO_3含量的增加(或Y_2O_3含量的减少)而单调下降，但下降的速度随着CeO_3含量的增加而变得越来越陡峭。晶粒度依赖关系可用Hall-Petch关系很好地近似。因此，这两个极端成分的硬度可用以下经验公式表示：Hv=1250-0.90(T-293)+100(d^&lt；-0.5&gt；-1.21)对于3y-TZPHv=950-0.68(T-293)+430(d^&lt；-0.5&gt；-0.72)对于12Ce-TZP，T表示温度(K)和d的晶粒度(以微米为单位)。成分对相变温度的影响上述实验中使用的样品，除了少数样品外，不会通过冷却到液氮温度而发生转变。因此，制备了氧化钇含量较低的样品，用于MS和AS温度测量。这些温度由下列方程表示：0&lt；Y&lt；3ms=1279-364Y(0&lt；Y&lt；1.5)。由于2Y的ms低于77K，当Y含量超过2mol%时，AS-MS测得的驱动力迅速增大。这不能用自由能变化或硬度随Y含量的增加来解释。有必要进行进一步的研究来解释这种ms温度的剧烈变化。