纳米钛合金成分聚集的改进Miedema模型

Modified Miedema Model for Component Segregation of Nano Ti Binary Alloys

考虑表面效应,利用改进Miedema模型推导得到纳米二元合金形成焓的计算公式,并将它用于二元Ti-M(M=Si,Fe,Zn,Tc,Cd,Re,Os,Pb,Bi)纳米合金形成焓的研究。结果表明,对于同一成分的纳米合金来说,随着晶粒粒径的减小,形成焓增加,合金稳定性降低。晶粒尺寸在10nm以下时,成分聚集现象十分明显,合金的聚集方向和聚集程度由聚集驱动能控制。

Taking account of the surface effect,the formula for the calculation of the formation enthalpy of nano Ti binary alloys was deduced by modified Miedema model. And the formula was used to study the formation enthalpy of Ti-M （M=Si,Fe,Zn,Tc,Cd,Re,Os,Pb,Bi） nano binary alloys. The results show that the formation enthalpy and structure stability are affected by the grain size for Ti binary alloys with the same composition. That is to say,the smaller the particle size,the greater the formation enthalpy and the worse the structure stability. Also,the component segregation for the nano Ti binary alloys is very clear when the grain size is less than 10 nm. The direction and the degree of aggregation are controlled by the aggregation driving energy.