正电子寿命谱结果表明,在由非晶晶化法制备的大块纳米晶(晶粒尺寸为1—100nm)合金的界面处存在两类缺陷:自由体积型缺陷和纳米空洞.前者尺寸小于一个单空位,后者约为几个单空位大小,且通常位于几个晶界的交叉点处.两者相比,自由体积型缺陷是一种浅的捕获势,但其数量可占90%以上.值得注意的是随着晶粒的粗化,纳米空洞的尺寸和浓度将发生显著的变化.因此可以想象这种类型的缺陷将对纳米晶材料的界面结构及性能产生极大的影响.目前有关这方面工作的报道很少. Positron lifetime spectroscopy results show that there are two types of defects at the interface of bulk nanocrystals (grain size 1-100 nm) prepared by amorphous crystallization: free volume type defects and nano-voids, the former size is less than one Single vacancy, which is about the size of a few single vacancies, and is usually located at the intersection of several grain boundaries. In contrast to the two, free volume defects are a shallow capture potential, but their number can account for more than 90% It is noteworthy that with the coarsening of the grains, the size and concentration of the nano-voids will change significantly, so it is conceivable that this type of defects will have a drastic effect on the interfacial structure and properties of the nanocrystalline materials. There have been few reports of work in this area.