R-curve behavior and crack-closure stresses in barium titanate and (Mg,Y)-PSZ ceramics
R-curve behavior and crack-closure stresses in barium titanate and (Mg,Y)-PSZ ceramics
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DOI：
10.1111/j.1151-2916.2000.tb01197.x
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发表时间：
2000-02-01
影响因子：
3.9
通讯作者：
Schneider, GA
中科院分区：
文献类型：
--
作者：
Meschke, F;Raddatz, O;Schneider, GA
使用紧凑拉伸 (CT) 样品研究了钛酸钡 (BaTiO3) 和部分稳定氧化锆 (PSZ) 的 R 曲线、加工区域和屏蔽应力。 BaTiO3 和 PSZ 表现出明显的 R 曲线，该曲线在相似的裂纹长度上上升，并分别表现出 0.7 和 6.4 MPa.m(1/2) 的稳态韧性。两种稳态韧性相似，比初始断裂韧性大 80%，铁弹性域转换是 BaTiO3 的主要增韧机制，而在 PSZ 中，相变增韧是主要的增韧机制。使用原子力显微镜详细研究了每种材料的裂纹加工区和裂纹张开位移（COD）轮廓。使用权重函数方法从 COD 剖面中提取裂纹闭合应力分布。所得应力分布表明，BaTiO3 中 40 MPa 的残余压应力和 PSZ 中 400 MPa 的残余压应力作用于裂纹尖端后面的有限区域。在 PSZ 中，裂纹桥接似乎是相变增韧的竞争机制。
R-curves, process zones, and shielding stresses of barium titanate (BaTiO3) and partially stabilized zirconia (PSZ) have been studied using compact-tension (CT) specimens. BaTiO3 and PSZ exhibited pronounced R-curves that rose over similar crack lengths and showed steady-state toughnesses of 0.7 and 6.4 MPa.m(1/2), respectively. Both steady-state toughnesses were similar to 80% larger than the initial fracture toughnesses, Ferroelastic domain switching was the main toughening mechanism in BaTiO3, whereas, in PSZ, transformation toughening was the main toughening mechanism. The crack process zone and crack-opening-displacement (COD) profile of each material was studied in detail using atomic force microscopy. Cracks closure-stress distributions were extracted from the COD profiles, using weight-function methods. The resulting stress profiles indicated that compressive residual stresses of 40 MPa in BaTiO3 and 400 MPa in PSZ acted in a limited region behind the crack tip. In the PSZ, crack bridging seemed to be a competing mechanism to transformation toughening.