Elastic properties of Ti and its alloys nanostrctured due to severe plastic deformation

Abstract

Studies of elastic properties of titanium and its alloys processed by severe plastic deformation are presented. The evolution of the modulus of elasticity resulting from the transformation from a coarse-grained state to an ultrafine-grained one due to severe plastic deformation (SPD) was investigated. The acoustic composite oscillator technique was used to measure the elastic modulus in a wide strain amplitude range. The microstructure was studied in detail by scanning electron microscopy and electron backscatter diffraction methods. Parameters of nanoscale porosity were measured by small-angle X-ray scattering before and after treatment with a high hydrostatic pressure (1.5 GPa). In addition, densities of titanium and its alloys in various structural states were determined by the precision method of hydrostatic weighing. As experiments showed, noticeable changes in the elastic properties resulting from the change in the grain state can be attributed to several factors, such as dislocations, nanoporosity, high internal stresses, and the structure of the materials before SPD processing.