多晶Nb的纳米压痕研究

晶界硬化和滑移越过晶界传播的机制是材料变形研究中的两个重要问题，纳米压痕技术是研究滑移与晶界关系的有效手段之一．本文利用这一技术研究了多晶Nb晶界附近的变形行为，结果表明，当压痕打在一些晶界附近时，诱导了一种位移突变现象即晶界pop-in现象．与对应于材料初始塑性的pop—in不同，这种晶界pop-in现象与晶界二侧晶粒取向差密切相关．晶界pop—in与晶界附近硬度的变化无明显关联．

Nanoindentation Study of Polycrystal Nb

Grain boundary hardening and slip transmission across grain boundary are two important aspects in deformation of materials. Using depth-sensing indentation, a pop-in phenomenon induced by grain boundaries has been observed in polycrystalline niobium. This phenomenon is about a sudden displacement jump observed near a grain boundary segment at a larger force than the initial elasto-plastic pop-in, which is observed not to be affected by grain boundary. The experimental results show that this pop-in effect has a close relationship with misorientations of the grain boundary. Further studies found that no evident change of grain boundary hardness was observed even though there existed grain boundary pop-in.