Continuous microstructure evolution of ball rolled TWIP Ti15Mo alloy and its effect on phase precipitation behavior

Journal Article · Thu Nov 15 04:00:00 EST 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.08.032· OSTI ID:22805840

Min, Xiaohua; Yao, Kai; Zhou, Xueyin ^[1]; Emura, Satoshi; Tsuchiya, Koichi ^[2]

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1. School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)
2. Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

Highlights: • Gradient microstructure was induced by ball rolling method in a Ti15Mo alloy. • Twin density increased and then decreased as increasing distance from surface. • Ultrafine (α + β) duplex structure was formed in the heavily deformed region. • α-phase in plate was precipitated in twined region in slightly deformed region. • Strengthening by formation of sub/nano-grains was notable than that by twins. - Abstract: A β-type Ti15Mo alloy with {332}<113> twinning-induced plasticity (TWIP) effect was utilized to investigate the continuous microstructure evolution of β-matrix by ball rolling method. Precipitation behavior of α-phase and strengthening mechanism were examined in regions with different strain. Amounts of intersected twins were present in the slightly deformed region of β-matrix, and their area fraction decreased with an increase of distance from rolled surface. The β-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 α-phase with strong variant selection. Equiaxed α-phase preferentially nucleated at the boundaries of subgrains and nanograins with weak variant selection to form the ultrafine (α + β) 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 (α + β) duplex structure exhibited a better strengthening effect than that by precipitation of plate-like α-phase. The diversities of deformation microstructure combined with different precipitation behaviors of α-phase are desirable for controlling the mechanical properties of β-type TWIP titanium alloys.

• OSTI ID: 22805840
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 145; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BINARY ALLOY SYSTEMS
DEFORMATION
DISLOCATIONS
DISTANCE
MICROSTRUCTURE
MOLYBDENUM COMPOUNDS
NANOSTRUCTURES
NUCLEATION
PLASTICITY
PRECIPITATION
ROLLING
STRAIN HARDENING
SURFACES
TITANIUM COMPOUNDS