Mechanical behavior and microstructural evolution during cyclic tensile loading-unloading deformation in metastable Ti–10V–2Fe–3Al alloy

Abstract

The mechanical behavior and microstructural evolution for Ti–10V–2Fe–3Al (Ti-1023) alloy with a single metastable β-grains obtained by β solution treatment (β-ST) were discussed by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) during the various early stages of cyclic tensile loading-unloading deformation (abbreviated as cyclic deformation) at ambient temperature. The main deformation product is stress-induced martensite transformation (SIMT) by coupling mechanical characterization and microstructure observation. With the cycles increasing, the trigger stress of SIMT (σSIMT) decreases with a stress plateau (120 MPa ±10), and the volume fraction of SIMT gradually increases until a nearly complete α″ martensite microstructure. Besides, the deformation-induced martensite twins (DIMT) in the α″ martensite have been generated until reaching a certain strain value. Moreover, there is specific orientation relationships (SORs) between β matrix and α″ martensite with <100>β//<100>α″, <110>β//<010>α″, and <110>β//<001>α″. And the geometrically necessary dislocations (GNDs) structure evolution is sensitive to cyclic strain and grain orientation. Moreover, GNDs synergizes the microstructure evolution and mechanical behavior.