The microstructure and formation mechanism of face-centered cubic Ti in commercial pure Ti foils during tensile deformation at room temperature

Abstract Two variants of face-centered cubic (fcc) Ti phase appear in ultra-thin commercial pure Ti foils with hexagonal closed packed (hcp) structure during tensile deformation at room temperature. The orientation relationship between fcc-Ti phase and hcp-Ti matrix is determined as 〈0001〉 HCP  // 〈001〉 FCC , 〈11 2 ¯ 0 〉 HCP  // 〈1 1 ¯ 0 〉 FCC and 〈01 1 ¯ 0〉 HCP  // 〈110〉  FCC . The fcc-Ti phase with a habit plane of {01 1 ¯ 0} HCP usually nucleates at grain boundary and grows along the direction of 〈11 2 ¯ 0 〉 HCP . The thickness of fcc-Ti phase with a shape of thin plate ranges from 10 nm to 200 nm. Dislocations, steps and stacking faults with a space of 0.58 nm can be seen in fcc-Ti. The formation of a five-layer fcc-Ti can be accomplished by the formation of stacking faults and gliding of 1/6[11 2 ¯ 0 ] Shockley partial dislocations on the prismatic plane of hcp-Ti. The 1/3[11 2 ¯ 0 ] dislocations in hcp-matrix can cross the fcc-Ti phase because the Burgers vector of these dislocations is coincidence with 1/2[110] dislocations in the fcc-Ti.