冷速对液态Ti_3Al合金快速凝固过程中微观结构变化的影响

The Effect of Cooling Rate on the Microstructure Change During Rapid Solidification of Liquid Ti_3Al Alloy

采用分子动力学方法模拟研究了不同冷速条件下液态Ti3Al合金的凝固过程。采用对相关函数法、原子团类型指数法(CTIM)对凝固过程中团簇结构的变化进行了分析。结果表明:在以1×1012K/s,1×1013K/s,1×1014K/s三种不同冷速条件下,系统都形成了以(12 0 12 0)基本原子团为主的非晶态结构,冷速对于Ti3Al合金凝固过程微观结构的影响主要是通过(12 0 12 0)基本原子团数目变化体现出来,(12 0 12 0)基本原子团在Ti3Al合金快速凝固过程团簇结构演变中起了主要作用。冷速越低,Ti3Al合金的玻璃态转化温度越低,体统形成的(12 0 12 0)基本原子团数目越多,非晶体的结构越稳定。

A simulation study has been performed for the solidification of liquid Ti3A1 alloy at different cooling rate by molecular dynamics method. The pair distribution function g（r） curves and the cluster-type index method were used to analyze the changes of clusters structures during rapid solidification processes. It is showed that amorphous structures are formed mainly with the basic cluster （12 0 12 0） at the cooling rate of 1 x 10nK/s,1 x 10~3K/s and l x 10~4K/s in the system. The effect of cooling rate on the structure during solidification process of liquid Ti3 A1 alloy is mainly reflected by changes in the number of the （ 12 0 12 0） basic cluster. The basic cluster （ 12 0 12 0） plays a key role in evolution of cluster structures during rapid solidification processes. With lower cooling rate, there are more number of the （ 12 0 12 0）basic clusters formed, the amorphous structure is more stable.