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采用分子动力学模拟方法研究了不同尺寸Au纳米颗粒在烧结过程中晶型转变及烧结颈长大机制.研究发现纳米颗粒的烧结颈生长主要分为两个阶段:初始烧结颈的快速形成阶段和烧结颈的稳定长大阶段.不同尺寸纳米颗粒烧结过程中烧结颈长大的主要机制不同:当颗粒尺寸为4 nm时,原子迁移主要受晶界(或位错)滑移、表面扩散和黏性流动控制;当尺寸在6nm左右时,原子迁移主要受晶界扩散、表面扩散和黏性流动控制;当颗粒尺寸为9 nm时,原子迁移主要受晶界扩散和表面扩散控制.烧结过程中Au颗粒的fcc结构会向无定形结构转变.此外,小尺寸的纳米颗粒在烧结过程中由于位错或晶界滑移、原子的黏性流动等因素会形成hcp结构.
The molecular dynamics simulation method was used to study the crystal transformation and sintering neck growth mechanism of Au nanoparticles with different sizes during the sintering process. It was found that the sintering neck growth of the nanoparticles is mainly divided into two stages: the rapid formation stage of the initial sintering neck and The main mechanism of the growth of sintering neck during the sintering process of nanoparticles with different sizes is different: when the particle size is 4 nm, the atomic migration is mainly caused by the sliding of grain boundaries (or dislocations), surface diffusion and sticking When the size is about 6 nm, the atomic migration is mainly controlled by the grain boundary diffusion, surface diffusion and viscous flow control. When the particle size is 9 nm, the atomic migration is mainly controlled by grain boundary diffusion and surface diffusion. During sintering The fcc structure of Au particles will transform to amorphous structure.In addition, the small size of nanoparticles in the sintering process due to dislocation or grain boundary slip, the viscous flow of atoms and other factors will form hcp structure.