X-RAY STUDY OF ROLLED SINGLE CRYSTALS OF TI-48%NI-2%FE ALLOY. PART I : TEXTURE DEVELOPMENT AND MECHANISMS OF PLASTIC DEFORMATION

Rolled single crystals of the alloy Ti–48%Ni–2%Fe were studied by methods of X-ray diffractometry using a PSD-technique. Single crystals, consisting of the phase B2, were rolled in 11 initial orientations at 350°C with deformation degrees up to ~80%. Texture development in single crystals under rolling was analyzed to determine the acting mechanisms of plastic deformation. Three stable orientations of single crystals were found: {011}〈011〉 ,{111}〈011〉 and {111}〈112〉. It was shown on the basis of texture data, that Ti–Ni single crystals deform by means of combined action of slip in the systems {011}〈001〉 and twinning. For the first time, along with twinning in the known systems {114}〈221〉 , twinning in the systems {118}〈441〉 was revealed. A number of concrete cases was considered to refine the contributions of slip and twinning into reorientation of single crystals depending on their initial orientations as well as to ascertain the interrelation of different mechanisms.