In situ TEM observation of HCP to FCC transitions in hexagonal close-packed titanium.

It remains controversial as to whether a face-centered cubic (FCC) phase exists in pure titanium (Ti) upon deformation, since the FCC structures in deformed Ti may well be TiH_x resulting from the sample preparation process. Here, by using in situ transmission electron microscopy (TEM), we uncover direct evidences on the nucleation and growth of FCC-Ti right in front of the crack tip in the α-Ti matrix. Atomic resolution images further reveal that the transformation can be mediated by either partial dislocations on basal planes or shear and atomic shuffle on the FCC1 1 0|HCP1 0 -1 0 interfaces. IMPACT STATEMENT: FCC-Ti's formation in pure α-Ti through deformation is controversial. In situ TEM observed FCC-Ti nucleation and growth in α-Ti matrix near the crack tip and revealed the mechanism. [ABSTRACT FROM AUTHOR]