用正交偏振光显微镜,通过原位观察研究了恒位移下BaTiO_3单晶贯穿裂纹快速扩展与畴变的关系,以及在室温空气中(湿度为35%RH)亚临界裂纹扩展和畴变的关系。结果显示,加载开始时首先出现畴变,且其体积分数随载荷升高而增大;当载荷达到临界值时,裂纹快速形核、扩展并止裂,在空气中保持恒位移,畴变能慢慢发生,即空气中水吸附能促进畴变,当畴变发展到临界条件时就引起裂纹的亚临界扩展(即应力腐蚀)。 The relationship between the rapid propagation and the domain change of the BaTiO_3 single crystal through-hole crack was studied by in-situ observation with in-situ observation, and the relationship between the subcritical crack growth and the domain change in the air at room temperature (humidity 35% RH) . The results show that the first domain change occurs at the beginning of loading, and its volume fraction increases with the increase of load. When the load reaches the critical value, the crack nucleates rapidly, expands and stops, keeps constant displacement in the air, Slowly, water adsorption in the air can promote the domain change, when the domain change to the critical conditions to cause subcritical crack propagation (ie, stress corrosion).