微量元素对Al-Ag合金时效早期微结构演变影响的Kinetic Monte Carlo模拟研究

Effect of Microelements on the Microstructural Evolution of Al-Ag Alloys during Initial Aging Stage by Kinetic Monte Carlo Model

采用基于Multi-States Ising Model的Kinetic Monte Carlo算法,模拟研究了添加微量元素对Al-Ag合金时效初期微观结构的演变过程的影响。结果表明:在Al-Ag合金中,In,Sn,Be元素显著地抑制了合金时效初期的Ag原子偏聚,这是这些元素的原子与空位强烈地相互作用的结果。Mg元素对Ag原子的偏聚的抑制次之,添加Mg元素的合金,时效过程中出现了Mg-Ag原子团簇和Ag-Mg-Va团簇,Mg-Ag之间以及Mg-Va之间的共同作用影响了Ag原子的偏聚。Li,Cd原子与Ag原子和空位均无明显作用,因此Li和Cd元素对时效早期Ag原子的团聚影响较小。微量元素是通过与构成析出相的主要溶质元素以及空位的相互作用来实现对原子偏聚过程的影响,进而来影响Al-Ag合金的时效过程的,其中微量元素与空位的相互作用起到关键的作用。锁定单空位和空位团聚进而降低空位可动性是影响Al-Ag合金时效过程的两种重要机制。

The kinetic Monte Carlo method based on the Multi-States Ising Model, was applied to simulate the effect of microelements on the microstructural evolution of Al-Ag alloys during initial aging stage. The results show that the microelement In, Sn and Be have dramatic depression effects on the Ag clustering due to strong tendency to coexist with vacancy clusters. The Mg has a little depression effect on the Ag clustering compared to In, Sn and Be. There are Mg-Ag co-clusters and Ag-Mg-vacancy co-clusters in the Al-Ag alloy containing Mg. The interactions between Mg and Ag, Mg and Vacancy, lead to the restrained Ag clustering. The Li and Cd have little interaction with Ag and vacancy, so they influence Ag clustering slightly. The microelements influence the atom segregation during aging mainly by the interaction of vacancy and solute atoms of precipitated phase. The interaction of microelements and vacancy play a more important role. The ＂single vacancy locked＂ and ＂vacancy clusters collapse＂ are two important mechanisms to affect the aging process by vacancy mobility.