Ti_(2)AlNb合金的嵌入原子势

Embedded-atom method potential for Ti_(2)AlNb alloys

分子动力学模拟是一种行之有效的计算机模拟方法;然而,由于缺少合适的多元合金原子间势,因而限制了分子动力学模拟的应用.多元合金原子间势的开发一直具有挑战性.本文在嵌入原子势模型的框架下,提出一种适用于三元有序合金的原子间势构建方法,并开发了适用于原子尺度力学行为模拟的Ti_(2)AlNb合金新型原子间势.该势能够很好地再现B2-Ti_(2)AlNb的弹性常数、未弛豫的空位形成能、置换原子形成能、换位原子形成能、表面能和三种有序构型(B2相、D0_(19)相、O相)在不同体积下的内聚能.为了进一步检验势函数,计算了B2相的E-V曲线,结果与Rose曲线符合得很好;利用分子动力学模拟研究了B2相的熔化转变过程,结果大致反映了实验情况.本文的工作一方面为开发多元合金原子间势提供一种途径,另一方面为模拟计算Ti_(2)AlNb合金的工作者提供一种选择.

Molecular dynamics simulation is an effective computer simulation method.However,owing to the lack of suitable interatomic potential of multicomponent alloys,the application of molecular dynamics simulation is limited.The development of interatomic potential of multicomponent alloys has always been challenging.In this work,under the framework of EAM model,a construction method of interatomic potential suitable for ternary ordered alloys is proposed,and a new interatomic potential of Ti_(2)AlNb alloys suitable for atomic-scale mechanical behavior simulation is developed.The potential can well reproduce the elastic constants of B2-Ti_(2)AlNb,unrelaxation vacancy formation energy,substitutional atom formation energy,transposition atom formation energy,surface energy and cohesive energy of three ordered phase(B2,D0_(19) and O phases)in different volumes.To further test the potential functions,1)the E-V curve of B2 phase is calculated,and the result is well consistent with Rose curve;2)the melting transformation process of B2 phase is studied by molecular dynamics simulation,and the results roughly reflect the experimental fact.The present work provides a way to develop the interatomic potential of multicomponent alloys,and a option for the workers who simulate and calculate the Ti_(2)AlNb alloys as well.