用正电子湮没研究NiAl中的晶体缺陷

用正电子湮没技术研究了金属间化合物NiAl的结构缺陷、淬火缺陷和电子辐照缺陷,观察了淬火缺陷和辐照缺陷的回复行为。发现在280℃左右和500℃左右有两个明显的回复阶段。实验结果分析表明:低温回复是由于空位对的退火,而高温回复是由于单空位的退火而引起,并且NiAl中空位和晶格间隙处的导电电子密度较接近,但空位处的导电电子的动量比晶格间隙处的低。 关键词：

STUDY OF THE LATTICE DEFECTS IN NiAl BY POSITRON ANNIHILATION

The structural defects, quenching defects and electron-irradiation defects in the in-termetallic compounds NiAl have been studies with the positron annihilation technique. The recovery behaviour of quenching defects and irradiation defects have been inversti-gated. Two distinct recovery stages have been, found, one at about 280℃ and the other at about 500℃. The experimental results show that the low-temperature stage is due to the annealing out of the divacancies and the high-temperature stage is due to the annealing out of the vacancies; and the density of the conduction electrons at the vacancies and the lattice interstitial sites are nearly equal to each other, but the momentum of the conduction electrons at the vacancies is lower than that at the latties interstitialsites in NiAl.