Mg-PSZ陶瓷热处理与四方析体马氏体相变温度关系的研究

STUDIES ON RELATIONSHIP BETWEEN HEAT TREATMENT AND MARTENSITIC TRANSFORMATION TEMPERATURES OF t-PRECIPITATES IN Mg-PSZ CERAMICS

采用带有液氮负温裝置的LK-02型高速淬火膨胀仪对已获得工业应用的、含10mol％MgO的Mg-PSZ陶瓷的热处理条件与其中t-ZrO_2的马氏体相变温度(M_4、M_6)及可相变t-ZrO_7析体量的关系进行了研究,认为:t-ZrO_2析体的粒径及其热处理过程中的应力应变状态是决定或影响马氏体相变温度高低和在应力诱导下可相变t-ZrO_2量的两个基本因素;采取1420℃和1100℃的综合热处理,与在1420℃或1100℃进行单一温度热处理相比,易于控制M、和M_4值,且能保证较高的可相变t-ZrO_7析体量,是优化Mg-PSZ结构和性能的一种值得进一步进行研究的热处理工艺。经1100℃、4b热处理的Mg-PSZ试样的“Δl-T”曲线的低温端未观察到明显的表征马氏体相变的膨胀效应。

The relationship between heat treatment conditions and martensitic transformation temperatures(M_?, M_t) as well as transformable fraction of t-ZrO_2 precipitates in Mg-PSZ ceramics containing 10 mol％ MgO are studied in the paper. It is assumed that the particle size of t-ZrO_2 precipitates and their stress-strain state developed in heat treatment are two fundamental factors determining or affecting the martensitic transformation temperatures and the volume fraction of stress-induced transformable t-ZrO_2.Heat treatment both at 1420℃ and 1100℃ is more favorable for controlling M_?. and M_? than simply at 1420℃ or 1100℃, giving higher volume fraction of transformable t-ZrO_2 precipitates, and so is a promising new technique of heat treatment which would optimize the structure and properties of Mg-PSZ ceramics. At the low temperature end of the 'Δl-T' curve of Mg-PSZ specimen treated at 1100℃ for 4h there is no pronounced expansion effect characterizing martensitic transformation.