Abstract
High-strength titanium alloys are necessary and essential in aviation and aerospace fields. Attempt to enhance the strength of the most widely used Ti-6Al-4V alloy is significant. However, it is hard to obtain high strength (>1300 MPa) combining with adequate ductility (elongation>12%) for this alloy. In this study, Ti-6Al-4V alloy with high yield strength (1280 MPa), excellent ultimate tensile strength (1358 MPa) and proper elongation (13.7%) was successfully prepared by an innovative strategy based on electropulsing. The strong electron flow of electropulsing induced rapid temperature rise and yielded instantaneous phase transformation, which limited alloying elements diffusing and parent β size growing, and followed by different phase transformations in Al or V solute enriched regions in one parent β grain during the cooling process. The particular microstructure evolution resulted in efficient α′ lath refinement. Then, the strength can be greatly enhanced by the decomposition of fine α' after subsequent aging. Meanwhile, the V and Al generally kept the initial microstructural partition and resulted in a novel bi-lamellar microstructure, which led to proper ductility. The results and analysis provide a novel method and new idea to improve and control the mechanical properties of Ti-6Al-4V and other titanium alloys.
NSTL
Elsevier