多元Ti-Cu基合金非晶形成过程的分子动力学模拟与落管实验研究  

Amorphous solidification mechanism of multicomponent Ti-Cu based alloy investigated by molecular dynamics simulation and drop tube experiments

作　　者：徐山森 常健 翟斌 燕鹏旭 林茂杰 魏炳波[1] XU ShanSen;CHANG Jian;ZHAI Bin;YAN PengXu;LIN MaoJie;WEI BingBo(School of Physical Science and Technology,Northwestern Polytechnical University,Xi’an 710072)

机构地区：[1]西北工业大学物理科学与技术学院,西安710072

出　　处：《中国科学：技术科学》2024年第3期477-489,共13页Scientia Sinica(Technologica)

基　　金：国家重点研发计划(编号:2021YFA0716301);国家自然科学基金(批准号:52088101&51771154);陕西省重点研发计划(编号:2023-YBGY-437)资助。

摘　　要：采用DeePMD计算方法和落管快速凝固实验技术,研究了液态Ti_(41.5)Cu_(37.5)Ni_(7.5)Hf_(5)Sn_(5)Zr_(2.5)Si合金的非晶凝固机制.分子动力学计算结果显示,液态合金原子的总第一近邻配位数随系统温度的降低而增加,而Ti原子的第一近邻原子数则随着温度的降低而减少.同时,随着系统温度的降低,液态合金中二十面体和类二十面体团簇的数量显著增多,但中心Ti原子的比例却发生了衰减.在非晶凝固过程中,Ti原子表现出与大尺寸原子的弱亲和性和对二十面体团簇的弱构建性.在自由落体实验中,合金液滴所能达到的过冷度随液滴直径的减小而增大,其凝固组织主要由少量的富Cu相、极细的非规则(Ti_(2)Cu+TiCu)共晶和非晶相组成.当合金液滴直径减小至566μm时,合金凝固组织中开始出现非晶相,相应的临界过冷度ΔT_(C)为312 K(0.27T_(L)).非晶相体积分数随着液滴尺寸的减小而增大.如果合金液滴直径小于317μm,晶体相的形核与生长被完全抑制,凝固组织由全部非晶相组成.The amorphous solidification mechanism of liquid Ti_(41.5)Cu_(37.5)Ni_(7.5)Hf_(5)Sn_(5)Zr_(2.5)Si alloy was characterized by both the DeePMD simulation method and drop tube experiments.The MD calculation results revealed that a lower temperature increased the total coordination number of the first nearest neighbor atoms in liquid alloy,but reduced that of Ti atoms.The number of icosahedral and icosahedral-like clusters in the liquid alloy was also significantly increased with the temperature decreasing,whereas the proportion of central Ti atoms was obviously decreased.In the amorphous solidification process,Ti atoms exhibited weak affinity with largesized atoms such as Zr,Cu and Hf,and also showed a weak ability of structuring icosahedral clusters.Under free-fall conditions,alloy droplet undercooling increased with reduced diameter,and its solidification microstructure mainly consisted of a little amount of Curich phase,extremely fine irregular(Ti_(2)Cu+TiCu)eutectic and amorphous phase.When the alloy droplet diameter decreased to 566μm,an amorphous phase appeared in solidified microstructures which represented a critical undercooling of 312 K(0.27T_(L)).As the droplet size continued to decrease,the volume fraction of the amorphous phase gradually increased.When the alloy droplet became smaller than 317μm,the nucleation and growth of crystalline phases were suppressed,resulting in the realization of completely amorphous solidification.

关 键 词：非晶合金 分子动力学 液态结构 自由落体 深过冷 

分 类 号：TG139.8[一般工业技术—材料科学与工程]