金属玻璃Pd_(79.5)Ni_4Si_(16.5)结晶化过程的慢正电子束研究

Research for Crystallization of Metallic Glass Pd_(79.5)Ni_4Si_(16.5) by Slow Positron Beam

首次用单能慢正电子束研究金属玻璃的晶化过程。测量了金属玻璃Pd_(79.5)Ni_4Si_(16.5)淬火态、结构弛豫和结晶化状态样品的正电子湮没辐射多普勒展宽能谱与正电子入射能量的函数关系,结果表明,淬态金属玻璃Pd_(79.5)Ni_4Si_(16.5)中存在大量的空位型缺陷,其结晶化过程最先开始于表面层。单能慢正电子束是研究金属玻璃晶化过程的有效手段。

The monoenergetic slow positron beam was first used to study the crystallization process of metallic glasses. The measurement of Doppler broadening spectra as a function of positron energy was made on the samples of metallic glass Pd_(79.5) Ni_4 Si_(16.5) in various states. It is shown that there are a number of the vacancy-like defects in the as- quenched state sample. Its crystallization started at the sample surface. Slow position beam turned out to be an effec(?)ive probe to study the structural change of metallic glasses.