Microshear deformation of gold single crystals

We perform microshear experiments on Au single crystals, directly imposing shear loading on the microscopic crystallographic 〈1 −1 0〉 {1 1 1} slip system. We use a focused ion beam machined micro-double shear specimen which we load with a flat punch indenter inside a scanning electron microscope. Our method yields reproducible mechanical data (e.g. critical shear stresses of 63.5 ± 2.5 MPa). We study small-scale plasticity up to high strains (>50%) at constant slip geometry and document localized plastic deformation and sudden plastic deformation events. Strain bursts are observed, which can be related to the formation of new shear bands. Alternatively, they can result from sudden shear strain accumulation events in existing shear bands. Due to the stochastic nature of plastic deformation, the nature and the number of strain bursts can vary. We show and discuss how our in situ test technique captures these effects and how this affects the corresponding load–displacement curves. We discuss the advantages and inconveniences of our microshear test technique compared to other small-scale testing methods and relate our mechanical results to previous results reported for the micromechanical behavior of Au.