Investigation of Size Effects in Slip Strength of Titanium Alloys: α Nodule Size Dependence of the Critical Resolved Shear Stress

Reported critical resolved shear stress (CRSS) values for basal and prismatic slip of titanium alloys are presently reviewed. Despite different average compositions, CRSS variations appear as mostly related to the α nodule size. Investigations of tensile tests performed in a scanning electron microscope reveal that the underlying size effect results from back stress generated by dislocations piling up at nodule boundaries. A relationship is proposed to predict CRSS for alloys with a given nodule size.