Abstract
The face-centered cubic structure(fcc)and its deformation behaviors,as well as the distinctive role of fcc-Ti in nanocrystallization in TC17 subjected to high energy shot peening(HESP),were investigated by using comprehensive high-resolution transmission electron microscopy(HRTEM).The results showed that there was a stress-induced fcc-Ti in TC17 with a lattice constant of 0.420-0.433 nm and the B-type orien-tation relationship between the hcp-Ti and the fcc-Ti as[2-1-10]hcp//[-110]fcc and(0001)hcp//(111)fcc,which was accomplished by the gliding of Shockley partial dislocations with Burgers vector of 1/3[01-10]on the basal plane.The deformation twinning dominated the subsequent deformation of fcc-Ti,producing two types of{111}<11-2>twins with different characteristics.Among them,the I-type twin with complete structure was generated by successive gliding of Shockley partial dislocations with the same Burgers vec-tor of 1/6[11-2].In contrast,the cooperative slip of three Shockley partials,whose sum of Burgers vectors was equal to zero,produced the Ⅱ-type twin with zero net macroscopic strain.And then,the emission of Shockley partial with the Burgers vector of 1/6[11-2]on every three(111)fcc planes resulted in the for-mation of a 9R structure.Due to the dissociation effect of lamellar fcc-Ti and the superior deformation ability of fcc structure,the occurrence of fcc-Ti effectively promoted surface nanocrystallization of TC17.
基金项目
国家自然科学基金(51475375)
国家自然科学基金(51705425)
Shaanxi Province Postdoctoral Science Foundation(2017BSHEDII06)
维普
万方数据