Effects of Crystalline Anisotropy and Indenter Size on Nanoindentation by Multiscale Simulation

Junwan Li,Hongsheng Wang,Jifa Mei,Yushan Ni

doi:10.1007/s11671-009-9500-x

Abstract

Nanoindentation processes in single crystal Ag thin film under different crystallographic orientations and various indenter widths are simulated by the quasicontinuum method. The nanoindentation deformation processes under influences of crystalline anisotropy and indenter size are investigated about hardness, load distribution, critical load for first dislocation emission and strain energy under the indenter. The simulation results are compared with previous experimental results and Rice-Thomson (R-T) dislocation model solution. It is shown that entirely different dislocation activities are presented under the effect of crystalline anisotropy during nanoindentation. The sharp load drops in the load–displacement curves are caused by the different dislocation activities. Both crystalline anisotropy and indenter size are found to have distinct effect on hardness, contact stress distribution, critical load for first dislocation emission and strain energy under the indenter. The above quantities are decreased at the indenter into Ag thin film along the crystal orientation with more favorable slip directions that easy trigger slip systems; whereas those will increase at the indenter into Ag thin film along the crystal orientation with less or without favorable slip directions that hard trigger slip systems. The results are shown to be in good agreement with experimental results and R-T dislocation model solution.

Highlights

Nanostructural materials have been the subject of intensive research in recent years due to its unique mechanical properties [1, 2]
The nanoindentation deformation processes under influences of crystalline anisotropy and indenter size are investigated about hardness, load distribution, critical load for first dislocation emission and strain energy under the indenter
It is shown that entirely different dislocation activities are presented under the effect of crystalline anisotropy during nanoindentation

Summary

Introduction

Nanostructural materials have been the subject of intensive research in recent years due to its unique mechanical properties [1, 2]. Using the QC method, Wang et al [34, 35] investigated the size effect of the indenter and the microscopic mechanisms of dislocation deformation during nanoindentation. Jin et al [37] studied the dislocation nucleation and interactions at the onset of plasticity for the nanoindentation of the (001) surface of a single crystal Al using the QC method. They found that the sharp load drops in the load–displacement curves are associated with deformation twinning and collective dislocation activities.

Rigid substrate

Results and Analysis

Discussion