Kinetic Measurement of the Martensitic Transformation in Y-TZP Samll Particles

在油中团聚法制备的500 μ m大小的小球形试样上研究了氧化钇掺杂氧化锆的马氏体相变动力学。主要研究结果如下：1.通过快速冷却和加热处理，可以研究小球形试样的相变动力学。对于含有少量氧化钇的氧化锆，快速淬火在室温下导致高度亚稳的四元相，氧化钇通常在通常的冷却速率下转变为大块试样。这一事实表明，马氏体相变涉及一个热激活过程.在中间温度下，亚稳的t相进行等温转变。动力学通过TTT图中的C曲线描述，上限为450 ℃，鼻部为350 ℃。亚稳t相在零度以下冷却时发生爆发转变。Ms温度位于-118 +-6 ° C。从上述观察，它被证实，亚稳的t-相经历等温和非热转变取决于热处理。这种现象不能用现有的马氏体形核理论来解释。

Kinetics of the martensitic transformation of yttria doped zirconia was studied on small spherical specimens of 500 mum size prepared by the agglomeration method in oil. The main results obtained are as follows :1. Small spherical specimens allowed to study the transformation kinetics by rapid cooling and heating treatments. Rapid quenching resulted in a highly metastable tetragonal phase at room temperature for the zirconia containing small amount of yttria which normally transform during the usual cooling rate for a bulk specimen. The fact suggested that the martensitic transformation involves a thermally activated process.2. The metastable t-phase underwent isothermal transformation when held at an intermediate temperature. The kinetics was described by a C-curve in the TTT diagram with an upper limit at 450ﾟC and a nose at 350ﾟC.3. The metastable t-phase undergoes a burst transformation during subzero-cooling. The Ms temperature was located at-1 18+-6ﾟC.4. From the above observation, it was verified that the metastable t-phase undergoes both isothermal and athermal transformations depending on the heat treatment. Such phenomenon cannot be explained by the existing theories of the nucleation of martensite.