Dislocation induced FCC twinning at the HCP/FCC interfaces in a deformed Ti-5at.%Al alloy: Experiments and simulations

H Zhang and BQ Wei and XQ Ou and S Ni and KC Zhou and M Song, JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 169, 110835 (2022).

DOI: 10.1016/j.jpcs.2022.110835

This paper proposes a new formation route for the face-centered cubic (FCC) twins at the hexagonal close-packed (HCP)/FCC interface in a deformed Ti-5at.%Al alloy. Experimental results show that a FCC band satisfying a prismatic-type (P-type) orientation relationship (OR) with the HCP matrix (defined as "P-type FCC band") is surrounded by a group of FCC lamellae that align in parallel and satisfy a basal-type (B-type) OR within the HCP matrix (defined as "B-type FCC lamellae"). High- resolution transmission electron microscopy reveals a local 111 twinning relation between the P-type FCC band and the B-type FCC lamellae at their contact boundaries. Molecular dynamics simulations indicate that basal stacking faults initiate from the misfit regions and evolve into the B-type FCC lamellae at the relaxed P-type HCP/FCC interfaces. Then mismatch provides the nucleation source for a full dislocation that continues to slip in the initial FCC grain. Repeating these two processes produces the 111 twinning relation between the new-forming FCC lamellae and the initial FCC grain. Lattice correspondence analysis further interprets the formation route for the 111 twins proposed in the present study from the aspect of crystal geometry.

Return to Publications page