Estimate of theoretical shear strength of C60 single crystal by nanoindentation

Sergey N Dub,Vitaliy M Kindrachuk,Cetin Haftaoglu

doi:10.1007/s10853-021-05991-2

Sergey N Dub, Vitaliy M Kindrachuk + Show 1 more

Open Access

https://doi.org/10.1007/s10853-021-05991-2

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Abstract

The onset of plasticity in a single crystal C60 fullerite was investigated by nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation in a contact was observed as pop-in events on loading curves. The respective resolved shear stresses were computed for the octahedral slip systems langle{01}overline{1}rangleleft{ {{111}} right}, supposing that their activation resulted in the onset of plasticity. A finite element analysis was applied, which reproduced the elastic loading until the first pop-in, using a realistic geometry of the Berkovich indenter blunt tip. The obtained estimate of the C60 theoretical shear strength was about {1}/{11} of the shear modulus on {111} planes.Graphical abstract

Highlights

Frenkel theoretically showed in 1926 that a shear stress required for initiation of plastic deformation in an ideal infinite crystal is sth 1⁄4 G=2p, where G is the shear modulus [1]
A significant discrepancy between the yield strength of real and ideal crystalline materials is caused by lattice defects, which facilitate the onset of plasticity during deformation
According to estimates gained by bending tests [3], their theoretical shear strength varies from G=15 to G=10

Summary

Introduction

Frenkel theoretically showed in 1926 that a shear stress required for initiation of plastic deformation in an ideal infinite crystal is sth 1⁄4 G=2p, where G is the shear modulus [1]. The onset of plasticity in a single crystal C60 fullerite was investigated by nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation in a contact was observed as pop-in events on loading curves.

Results

Conclusion