纳米Ir薄膜中缺陷结构的原子尺度研究

金属铱(Ir)因具有高密度,高熔点,高硬度等特点而被广泛应用于航空航天、军工等高新科技领域。但Ir的塑性差,严重影响其进一步广泛应用。金属自身的结构及缺陷对其力学性能具有重要影响,研究Ir的原子尺度微观结构可为其力学性能优化提供重要参考。本文主要利用透射电子显微镜(TEM)对纳米Ir薄膜中的缺陷类型和缺陷密度进行了研究。发现薄膜中存在高密度的孪晶以及位错。其中,薄膜中的孪晶密度为1.6×10³(1/μm²)。此外,研究还发现薄膜中有两大类缺陷的相互作用:位错与孪晶相互作用以及孪晶与孪晶相互作用。前者包括层错与孪晶相互作用以及全位错对孪晶的钉扎作用;孪晶之间的相互作用形态包括头对头对接式,三重孪晶和五重孪晶等多种形态。

Investigation of the atomic-scale structure of defect in nano iridium thin films

Iridium(Ir)is widely used in aerospace,military and related high-tech fields because of its high density,high melting point and high hardness.However,the poor plasticity of Ir affects its further application.It’s well established that the microstructure of metal,such as defect density,dislocation structure,twin boundary ect.can significant affect their mechanical properties.Thus,investigation of the atomic scale microstructure of Ir can provide important guidance for the optimization of its mechanical properties.In this paper,we investigated the defect types and defect density in Ir thin films by transmission electron microscopy(TEM).High density of twin and dislocation were observed in the thin film.The density of twin in the thin film is-1.6×10³(1/μm²).In addition,our observation revealed that there are two kinds of defect interaction in the film:dislocation-twin interaction,and twin-twin interaction.The former includes the partial dislocation interact with the twins,and the full dislocation pinning with twin boundary.The interaction between twins includes twin boundary head-to-twin boundary head type,as well as twin interaction resulted three fold twins and five fold twins.