多晶体材料的晶界强化模型研究

近几十年来,材料的细晶强化研究大量开展。在一般晶粒尺寸范围内,材料的强度随晶粒尺寸的变化是符合Hall-Petch关系的,但在纳米晶体材料中出现了偏离甚至反Hall-Petch关系的现象,因此Hall-Petch关系的使用具有一定的局限性。文章从塑性变形理论出发,建立了晶界强化数学模型,通过该模型,研究了晶粒大小、晶界厚度及晶界体积百分数、晶界能、弹性模量与多晶体材料强度的关系,发现除了晶粒大小及晶界厚度影响材料强度之外,弹性模量、晶界能越大,多晶体材料的强度越高。

Study on the grain-boundary strengthening model of polycrystalline materials

The grain-refining strengthening of metals has been the subject of considerable research in recent years.The relation between mechanical properties and grain size conforms to Hall-Petch relation.However,it was found that the mechanical properties deviate from or reverse the Hall-Petch relation.Therefore using the Hall-Petch relation has its limitation.In this paper,the mathematical model for grain-boundary strengthening is established starting from the theory of plastic deformation.The effect of grain size,grain-boundary thickness,fraction of grain-boundary volume,grain-boundary energy,and elastic modulus on the strength of polycrystalline materials is discussed through the obtained mathematical model.It is indicated that the strength of polycrystalline materials increases with the increasing of elastic modulus and grain-boundary energy.