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Indexed by:期刊论文

Date of Publication:2018-11-01

Journal:MATERIALS CHARACTERIZATION

Included Journals:SCIE

Volume:145

Page Number:116-125

ISSN No.:1044-5803

Key Words:Titanium alloy; Ball rolling; Twinning; Microstructure evolution; Precipitation behavior; Strengthening mechanism

Abstract:A beta-type Ti-15Mo alloy with {332}<113> twinning-induced plasticity (TWIP) effect was utilized to investigate the continuous microstructure evolution of beta-matrix by ball rolling method. Precipitation behavior of alpha-phase and strengthening mechanism were examined in regions with different strain. Amounts of intersected twins were present in the slightly deformed region of beta-matrix, and their area fraction decreased with an increase of distance from rolled surface. The beta-matrix close to surface was heavily deformed to result in the formation of abundant subgrains and nanograins, which was caused by cooperative occurrence of twinning refinement, intragranular dislocation activities and subgrain rotation. Mechanical twins provided the preferential nucleation sites for plate-like alpha-phase with strong variant selection. Equiaxed alpha-phase preferentially nucleated at the boundaries of subgrains and nanograins with weak variant selection to form the ultrafine (alpha + beta) duplex structure. Due to the formation of subgrains and nanograins as well as the strain hardening, strengthening became more significant than that by twinning refinement solely. Similarly, the ultrafine (alpha + beta) duplex structure exhibited a better strengthening effect than that by precipitation of plate-like alpha-phase. The diversities of deformation microstructure combined with different precipitation behaviors of alpha-phase are desirable for controlling the mechanical properties of beta-type TWIP titanium alloys.