Influence of visco-elasto-plastic properties of magnetite on the elastic modulus: Multicyclic indentation and theoretical studies

In the present work, we study the indentation behaviour of the magnetite coexisting with hematite in a natural dual-phase crystal. In particular we show the influence of cycling indentation conditions on the elastic modulus measurement in relation to the visco-elasto-plastic properties of the material. Elastic properties of Fe3O4 are investigated using Oliver and Pharr's technique, which is based on depth-sensing indentation (DSI) analysis. Depending on the visco-elasto-plastic properties of the material, the indentation test conditions (monotonic, cyclic, loading and unloading rates, dwell time at peak load, …) can modify the shape of the load–depth curve and, subsequently, the results. Molecular dynamics simulation based on shell model potential, is used to determine elastic quantities including elastic modulus, bulk modulus and Young modulus.