The work presents a detailed investigation of mechanical properties and deformation mechanism of ultrathin commercial pure Ti foils subjected to uniaxial tensile. The initial microstructure of the annealed Ti foils is fine equiaxed grains, with an average grain size of 3.3 µm. The main types of texture in pure Ti foils are {10 $\bar{1}$ 3} and {11 $\bar{2}$ 4}. Dimples, tear ridges and slip traces are found on the fracture surface, and the elongation reaches 16.7%. The large tensile elongation of pure Ti foils can be attributed to the slip of dislocations, twinning and phase transformation of HCP-Ti to FCC-Ti, which is confirmed by both X-ray diffraction and transmission electron microscope. The orientation relationship of the two phases is determined to be: <0001>_HCP // <001>_FCC, <11 $\bar{2}0$>_HCP // <1 $\bar{1}0$>_FCC and {01 $\bar{1}$ 0}_HCP // {110}_FCC. According to this relationship, the HCP to FCC phase transformation expands the volume of the unit cell by about 10.5%. Furthermore, the volume fraction of FCC-Ti is determined to be about 3.44%. Therefore, the transformation is expected to contribute about 3.6% to the applied strain.

这项工作提出了对单轴拉伸超薄商业纯钛箔的力学性能和变形机理的详细研究。退火的Ti箔的初始显微组织是细等轴晶粒，平均晶粒尺寸为3.3 µm。纯钛箔的主要织构类型为{10$\overline{\mathrm{1个}}$ 3}和{11 $\overline{\mathrm{2个}}$4}。在断口表面发现凹痕，撕裂隆起和滑动痕迹，伸长率达到16.7％。纯Ti箔的大拉伸伸长率可归因于位错滑移，HCP-Ti孪晶化和相转变为FCC-Ti，这已通过X射线衍射和透射电子显微镜得到了证实。确定两相的定向关系为：<0001> _HCP // <001> _FCC，<11$\overline{\mathrm{2个}}0$> _HCP // <1$\overline{\mathrm{1个}}0$> _FCC和{01$\overline{\mathrm{1个}}$0} _HCP // {110} _FCC。根据这种关系，从HCP到FCC的相变将单位晶胞的体积扩大了约10.5％。此外，确定FCC-Ti的体积分数为约3.44％。因此，预期该转变对所施加的应变贡献约3.6％。