压痕尺寸和晶粒/亚晶粒尺寸对高纯钨显微硬度的影响

摘要

通过对不同结构的高纯钨进行微米和纳米压痕实验，发现压痕尺寸和晶粒/亚晶粒尺寸对材料的硬度有重要影响。探讨硬度的晶界效应和压痕尺寸效应。采用Nix−Gao模型，结合尺度因子对实验获得的压痕硬度值进行拟合。结果表明，尺度因子几乎与晶粒或亚晶粒的尺寸无关。塑性变形区与晶界或亚晶界之间的相互作用是导致硬度在某一特定深度增加的原因，而塑性变形区与晶粒或亚晶粒的尺寸几乎无关。当塑性变形区扩展增大到单个晶粒或亚晶粒尺寸时，压痕硬度开始趋于稳定。%Hardness of materials depends significantly on the indentation size and grain/sub-grain size via microindentation and nanoindentation tests of high-purity tungsten with different structures. The grain boundary effect and indentation size effect were explored. The indentation hardness was fitted using the Nix−Gao model by considering the scaling factor. The results show that the scaling factor is barely correlated with the grain/sub-grain size. The interaction between the plastically deformed zone (PDZ) boundary and the grain/sub-grain boundary is believed to be the reason that leads to an increase of the measured hardness at the specific depths. Results also indicate that the area of the PDZ is barely correlated with the grain/sub-grain size, and the indentation hardness starts to stabilize once the PDZ expands to the dimension of an individual grain/sub-grain.