The indenter tip radius effect in micro- and nanoindentation hardness experiments

作     者：Fan Zhang Yonggang Huang Keh-Chih Hwang 

作者机构：FML Department of Engineering MechanicsTsinghua University Beijing 100084 China Dept. of Mechanical and Industrial EngineeringUniversity of Illinois Urbana IL 61801 USA 

出 版 物：《Acta Mechanica Sinica》 (力学学报（英文版）)

年 卷 期：2006年第22卷第1期

页      面：1-8页

核心收录：

学科分类：08[工学] 080102[工学-固体力学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：The project supported by the National Natural Science Foundation of China (10121202) the Ministry of Education of China (20020003023) 

主　　题：Taylor dislocation model Strain gradient plasticity Indentation Nix-Gao relation 

摘      要：Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer range）, but it does not always hold in nanoindentation experiments （indentation depths approaching the nanometer range）. Indenter tip radius effect has been proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao＇s relationship. We have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary dislocations. The comparison between numerical result and Feng and Nix＇s experimental data shows that the indenter tip radius effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.