Nanoindentation of Aluminum Single Crystals: Experimental Study on Influencing Factors.

Pavel Filippov,Ursula Koch

doi:10.3390/ma12223688

Pavel Filippov, Ursula Koch

Open Access

https://doi.org/10.3390/ma12223688

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Abstract

Results from nanoindentation of aluminum single crystals deliver valuable information as model systems for understanding technical aluminum alloys. The effect of the crystal orientation and the azimuthal indenter orientation on indentation hardness and modulus was studied by Vickers indentation (max. load 10 mN) on single crystal surfaces with (100), (110), and (111) orientations. The average indentation hardness varied, depending on the crystallographic orientation, by 1.8%. The anisotropy of the elastic modulus (1.1% of the average modulus) is lowered (indentation averaging effect). This is predicted by explicit approximation of the contact problem (conical indenter, orthotropic material). It was found that indentation hardness and modulus vary periodically with the azimuthal indenter orientation on (100)- and (110)-oriented surfaces (relative amplitude of 1.8% for indentation hardness and 2.6% of the modulus). This is attributed to the combined effect of the indenter geometry and crystal symmetry. For the first time, this effect was quantified for aluminum single crystals.

Highlights

Nanoindentation is a well-developed and widely used method for determining hardness and elastic modulus on different length scales ranging from several hundred micrometers to a few nanometers [1,2]
The results for the elastic modulus of metals achieved by nanoindentation often differ from theoretical values, as well as from results obtained from macroscopic methods, as pointed out by Shuman et al [6]
The aim of this research is to create an experimental basis for the dependency of indentation hardness and modulus on the crystallographic orientation of aluminum

Summary

Introduction

Nanoindentation is a well-developed and widely used method for determining hardness and elastic modulus on different length scales ranging from several hundred micrometers to a few nanometers [1,2]. This method is widely used to access nanomechanical properties of crystalline and amorphous and heterogeneous materials such as glasses, ceramics, or metals [3,4,5]. These properties are essential for micro-manufacturing of metallic materials. Attempts have been made to achieve a better understanding of the indentation process through simulation [8,9,10]

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