液态金属铝的热历史对凝固微结构的影响  

Effects of Thermal History of Liquid Metal Al on Its Solidification Microstructures

作　　者：刘让苏[1] 刘凤翔[1] 李基永[2] 董科军[1] 郑采星[1] 

机构地区：[1]湖南大学应用物理系 [2]湖南大学化学化工学院,长沙410082

出　　处：《物理化学学报》2003年第9期791-794,共4页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(50071021;50271026)~~

摘　　要：用分子动力学模拟研究了液态金属Al系统的热历史对凝固微结构的影响、发现在同一系统中、不同的热历史条件下,1551键型和与1551键型相关的二十面体结构(12 0 12 0)在微结构的转变过程中均起着非常重要的作用,特别有意义的是,在每个温度的等温运行中能够重复出现的二十面体的数目不随温度的降低而增加,并有一个极大值.该极大值点正好与其玻璃转变温度T_g相对应,在不同的热历史条件下极大值的位置是能够移动的.结果还显示出,热历史条件对微结构转变有严重影响,且其作用主要是在玻璃转变温度点T_g以后才显示出来.这就为我们理解和控制凝固过程中的微结构转变提供了一条新途径.The effects of thermal history of liquid metal Al on its solidification microstructures have been studied by using molecular dynamics simulation. It has been found that under different thermal history conditions, in the same system, both the 1551 bond-type and the icosahedron (expressed by (12 0 12 0)) related to the 1551 bond-type play a remarkable role during microstructure transitions(see Fig. 4). The number of repeatable icosahedra not always increased with the decrease of temperature and has a maximum during the isothermal runs at given temperatures (see Fig. 6). The maximum point corresponds to the glass transition temperature T-g, and can be moved under different thermal history conditions. It is also demonstrated that the thermal history conditions seriously influence the solidification microstructures and their effects are mainly demonstrated after the glass transition point. These results give a new way to understand and control the microstructure transitions during solidification processes.

关 键 词：液态金属铝 热历史 凝固 微结构 计算机模拟 分子动力学 

分 类 号：TG146.21[一般工业技术—材料科学与工程]