Evaluation of friction stresses in the γ phase of a nickel-base superalloy ‘In situ’ deformation experiments

Both ‘in situ’ experiments and ‘post mortem’ observations have been performed on single crystals from MC2 superalloy γ matrix. Based on the measurement of the dislocation positions within the observed pile ups, a method is proposed that allows the evaluation of friction stresses from the head to the tail of the moving or relaxed pile ups. It appears that friction stresses must be measured on mobile pile ups, when they are deduced from relaxed pile ups they are considerably underestimated.