CAJ | 학술논문

采用分子动力学模拟方法和团簇类型指数法,对过冷液态和非晶态金属Pb在等温驰豫过程中bcc相的形成和演变特性进行研究.结果表明:bcc相的形成和演变密切依赖等温驰豫过程的初始温度和初始结构,在过冷液态区,bcc相很容易形成并在模拟时间范围内保持稳定;而在非晶态区,bcc相先形成并随后部分转变为hcp相,当驰豫的初始温度在较低的153 K和113 K时,hcp和fcc相不经历亚稳bcc相而直接在非晶态结构中形成;这说明Ostwald的"步进原则"在过冷液态和非晶态Pb等温驰豫过程中是有效的,并且,亚稳bcc相起到重要的晶化前驱的作用.
채용분자동역학모의방법화단족류형지수법,대과랭액태화비정태금속Pb재등온치예과정중bcc상적형성화연변특성진행연구.결과표명:bcc상적형성화연변밀절의뢰등온치예과정적초시온도화초시결구,재과랭액태구,bcc상흔용역형성병재모의시간범위내보지은정;이재비정태구,bcc상선형성병수후부분전변위hcp상,당치예적초시온도재교저적153 K화113 K시,hcp화fcc상불경력아은bcc상이직접재비정태결구중형성;저설명Ostwald적"보진원칙"재과랭액태화비정태Pb등온치예과정중시유효적,병차,아은bcc상기도중요적정화전구적작용.
The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method (CTIM). It is found that during the relaxation process,the formation and evolution of bcc phase are closely dependent on the initial temperature and structure.During the simulation time scale,when the initial temperature is in the range of supercooled liquid region,the bcc phase can be formed and kept a long time; while it is in the range of glassy region,the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one,the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald's "step rule" is impactful during the isothermal relaxation process of the supercooled and glassy Pb,and the metastable bcc phase plays an important role in the precursor of crystallization.