High Temerature Plasticity of Metal/Ceramic Interface Free of Reaction Product Layer and Enhanced by Nonstoichiometry

今年，金属/陶瓷连接界面塑性的研究主要集中在以下三个不受反应产物层干扰的系统中：(1)Ni/Si_3N_4系统利用安装在高分辨电子显微镜上的高温测角台，通过改变样品箔温度，“原位”观察到Ni/Si_3N_4反应产物自由界面附近的热应力引起的变形。观察到界面位错的运动，但热应力松弛的主要机制是镍颗粒中晶格位错的运动。界面是位错的吸收位置，而不是发射位置。对断口的化学分析表明，烧结助剂在镍基高温合金与Si_3N_4的界面处发生了偏析。(2)Bi2Sr2Ca2Cu3Ox/Ag/Bi2Sr2Ca2Cu3Ox系统要将Bi超导氧化物用作约瑟夫森器件，银层是有用的。交流伏安特性表明，在界面结构有序的位置，[001]扭转双晶具有良好的择优取向性能。(3)C_&lt；60/石墨体系C_(60)在常温下为面心立方结构，塑性变形与金属相似。C&lt；60&gt；分子是通过真空沉积或用LB法拉起将C&lt；60&gt；固定在石墨的基面上。STM观察表明，该界面与Ag/Bi2Sr2Ca2Cu3Ox的界面不同，单层银原子平行于超导氧化物的a轴排列明显。

This year the research of plasticity at metal/ceramic joined interfaces has been concentrated with following three systems where the interfere is free of the reaction product layer.(1) Ni/Si_3N_4 systemUsing a high temperature goniometer stage mounted in a high resolution electron microscope, thermal stress induced deformation near the Ni/Si_3N_4 reaction product free interface has been observed "in situ" by changing the specimen foil temperature. The motion of interface dislocation has been observed, but the major mechanism of thermal stress relaxation has been the motion of the lattice dislocation in nickel grain. The interface acted as the site of dislocation absorption rather than emission. Chemical analysis of the fractured interface indicated the segregation of sintering additives at the interface between nickel base superalloy and Si_3N_4. (2) Bi_2Sr_2Ca_2Cu_3Ox/Ag/Bi_2Sr_2Ca_2Cu_3Ox systemIn order to use Bi-superconducting oxide as a Josephson device, silver thin layer is useful. The AC V-I characteristics indicated the performance of the [001] twist bicrystal is good at certain misorientation where the interface structure is ordered. (3) C_<60>/graphite systemCarbon 60 is face centered cubic at ambient temperatures and the plastic deformation is like that of metals. The C_<60> molecules were produced either by vacuum deposition or pulled up by LB method to mount C_<60> on the basal plane of graphite. The observation by STM showed that the interface is not like that of Ag/Bi_2Sr_2Ca_2Cu_3Ox where the allignment of monolayer silver atoms parallel to the a axis of the superconducting oxide was pronounced.