Mechanical properties improvement of titanium alloy and its grain boundary dislocation evolution mechanism by novel electroshock treatment

Abstract

Titanium alloys are extensively utilized in the aerospace industry due to their exceptional strength and resistance to corrosion. However, litmited performance and high dispersion has always existed for the traditional manufacturing process. A novel Electroshock Treatment (EST) procedure proposed by author's team can synergistically improve the mechanical properties and its consistency of titanium alloys under limited temperature rise, but the relevant mechanism is not yet clear. In present work, the effects of various EST conditions on the mechanical characteristics were investigated by uniaxial tensile testing, and the effect mechanism was revealed using multi-scale microstructure characterization of titanium alloys, such as SEM, EBSD and TEM. The uniaxial tensile test results show that, compared with the sample without EST, the average elongation after fracture improved by 12.5%, the strength-plastic product improved by 16.1%, and the consistency of UTS and elongation after fracture improved by 63.4% and 57.1%, respectively, with a slight increase of tensile strength (30 MPa) after appropriate treatment (current density of 0.93 × 10A/m, and pulse duration of 300 ms). The multi-scale microscopic characterization reveals a more uniform distribution of stress concentration in TC11 titanium alloy following the appropriate EST process. Besides, the entanglement of dislocations is reduced with some dislocations being annihilated. Especially, the remaining dislocations undergoing orderly rearrangement at grain boundaries after EST. The homogenization of local lattice distortion distribution and orderly rearrangement of dislocations at grain boundaries are the primary factors contributing to the comprehensive improvement in the mechanical properties and consistency of TC11 Titanium alloy.