Authors: M. Sob, M. Friák, and V. Vitek
Affilation: Academy of Sciences of the Czech Republic, Czech Republic
Pages: 279 - 282
Keywords: nanoindentation, theoretical strength, ab initio electronic structure calculations, onset of yielding
Quantum-mechanical (ab initio) approach for determining theoretical (ideal) tensile and shear strength in metals and intermetallics is briefly outlined and as an example, tensile test for defect-free MoSi2 is simulated. Theoretical values of tensile and shear strength are compared with those obtained from loading of whiskers and from nanoindentation experiments As nanoindentation tests can sample defect-free volumes the onset of yielding should correspond to theoretical shear strength. Possible sources of discrepancies between the measured maximum shear stress in nanoindentation experiments and theoretical values as well as corresponding corrections are discussed The calculated or measured values of theoretical strength may subsequently serve as input parameters to a quantitative and predictive model based on the properties of dislocation interactions that describes the relationship between the yield behaviour and length-scale effects in the nanoscale regime.