Detecting mechanical properties of microstructure units in Ti–6.5Al–3.5Mo–1.5Zr–0.3Si alloy

Strengths of microstructure units (i.e. α/β lamellae, colony boundary and prior β grain boundary) in the α/β lamellar-structured Ti–6.5Al–3.5Mo–1.5Zr–0.3Si alloy were examined using microindentation testing. Combining with the EBSD characterization, the relationship between the strength and the crystallographic orientation of the microstructure units was analyzed. The results show that the orientation of the α phase in α/β lamellae dominates the strength of the colony. The strength of the colony boundary can be determined by the strengths of the bilaterial colonies, following a rule of mixtures. Furthermore, the critical resolved shear stresses for the prismatic and the basal slip systems in the Ti–6.5Al–3.5Mo–1.5Zr–0.3Si alloy are evaluated based on the microindentation data.