非晶态合金Cu_xPd_(1-x)形成过程合金效应及微观结构转变特性的模拟研究(英文)

Simulation study on properties of microstructural transition and alloying effects during forming processes of amorphous Cu_xPd_(1-x)alloys

本文根据量子Sutton-Chen多体势,采用分子动力学方法对含有50000个原子大系统液态二元合金Cu_xPd_(1-x)(CuPd的原子半径比为1.14)在快速凝固过程中的微观结构转变特性进行模拟研究.运用Honeycutt-Andersen(HA)键型指数法和原子成团类型指数法(CTIM)分析了液态和固态的微观结构特性.研究结果发现:在7.73×10^(13)K/S冷却速率下,Cu_xPd_(1-x)合金形成以1551、1541和1431三种键型为主的非晶态结构;系统以1551键型和由1551键型构成的(12 0 12 0)二十面体团族在所有的键型和团簇中占主导地位,并且在液态合金Cu_xPd_(1-x)微观结构转变中起着关键性作用.通过分析键型、团簇和平均原子体积,我们发现液态合金Cu_xPd_(1-x)的玻璃转变温度是573K.同时还发现,原子的平均配位数的变化与1551,1441,1661键型的变化趋势相当接近,这反映出体系对称性结构的变化规律与配位数的变化有关.

Based on the quantum Sutton-Chen many-body potentials, a molecular dynamics simulation study has been adopted to investigate the features of microstructural transition of binary liquid alloys CuxPd1-x （the atomic radius ratio of the CuPd being 1.14）for a large-scale system consisting of 50000 atoms during the rapid cooling processes. To describe the complex microstructural properties in the liquid and solid states, the index method of Honeycutt -Andersen（HA） and the cluster-type index method （CTIM）have been used. It has been found that in the cooling rate of 7.73×10^13K/S, CuxPd1-x alloy fi- nally forms amorphous structures with the three bond-types of 1551.1541 and 1431 as the main body in the system. It is demonstrated that both the 1551 bond-type and the icosahedral cluster （12 0 12 0） constructed by 1551 bond-types ar＇e dominant among all the bond-types and cluster-types, and they play a critical and leading role in the microstructure transitions of liquid alloys Cu1Pd1-x. By analyzing the bond-types, clusters and average atomic volume,we find that the glass transition temperature Tg for liquid alloys CuxPd1-x is 573K. At the same time, it is still found that the variation of the mean coordina- tion number of atoms is rather close to that of 1551, 1441, 1661bond-types, this reflects that the varying rule of the symmetric configurations in system is related to the variation of the coordination num-ber.