Grain Boundary Design using Ceramic Multiple Crystals and Plasticity

在这一年中，系统地制造了氧化铝和氧化锆多晶体，并通过高分辨率电子显微镜（HREM）表征了各自的晶界结构和化学，能量色散X射线光谱（EDS）和电子能量损失光谱（EELS）在1500 ℃空气中采用热连接技术制备了Al 2 O3多晶，获得了10种倾斜晶界，角晶界、CSL晶界和高角晶界。结果表明，晶界能强烈依赖于晶界特征，在低α-CSL晶界处存在大的能量尖点。但晶界能的主要来源可能是晶界附近的应变能，原子组态的贡献不大。小角度晶界由伯格斯矢量为1/3[1 1^^- 00]的部分位错排列而成，位错间形成层错。关于BEH ...更多信息 通过1400 ℃高温蠕变试验，对典型晶界进行了晶界滑移的研究。结果表明，晶界滑移的发生与晶界几何结构和原子结构有关，并在1600 ℃空气中采用热连接技术制备了10种倾斜晶界。结果表明，晶界结构和能量强烈依赖于晶界特征。例如，尽管偏析的钇的量非常大，但由于结构单元在边界处高度应变，所以109晶界显示出特别高的能量。在边界为3的情况下，原子结构取决于边界平面。当边界面为（111）时，边界沿着（111）面完全是直的，然而，当初始边界面被设置为平行于（112）时，刻面结构沿着（111）//（115）面形成。从氧化锆中各种晶界的原子结构和偏聚的角度，详细讨论了晶界特征与能量的关系。少

In this year, alumina and zirconia multiple crystals were systematically fabricated, and the respective grain boundary structure and chemistry were characterized by high-resolution electron microscopy (HREM), energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS).Alumina multiple crystals were fabricated by a hot joining technique at 1500 ℃ in air to obtain ten kinds of tilt grain boundaries which included small angle, CSL and high angle grain boundaries. It was found that grain boundary energy strongly depended on the grain boundary characters, e.g., there were large energy cusps at low Σ CSL grain boundaries. But, main part of grain boundary energy is likely to be due to the strain energy around the grain boundary, and the contribution of atomic configuration is not so large. Small angle grain boundaries were consisted of an array of partial dislocation with Burgers vector of 1/3[1 1^^- 00] to form the stacking faults between the dislocations. The beh … More avior of grain boundary sliding was also investigated for typical grain boundaries by high-temperature creep test at 1400 ℃. As the result, the occurrence of grain boundary sliding was found to depend on the grain boundary geometry and atomic structure.Zirconia multiple crystals were also fabricated by a hot joining technique at 1600 ℃ in air to obtain ten kinds of tilt grain boundaries. It was found that the grain boundary structure and energy strongly depended on the grain boundary characters. For example, Σ9 grain boundary showed particularly high energy because the structure unit is highly strained at the boundary, although the amount of segregated yttrium is very large. In the case of Σ3 boundary, the atomic structure depends on the boundary planes. When boundary plane is (111), the boundary is perfectly straight along the (111) plane, however, facet structure is formed along (111)//(115) planes when the initial boundary plane is set parallel to (112). The relationship between grain boundary characters and energy will be discussed in detail from the view point of atomic structures and segregation for all kinds of grain boundaries in zirconia. Less