The assisting and stabilizing role played by ω phase during the 112111β twinning in Ti-Mo alloys: A first-principles insight. (30th July 2021)

• Record Type: Journal Article
• Authors: Chen, Qiu-Jie; Ma, Shang-Yi; Wang, Shao-Qing
• Is Part Of: Journal of materials science & technology. Volume 80(2021)
• Page Start: 163
• Page End: 170
• Publication Date: 2021-07-30
• Subjects: Titanium alloys -- Twin -- Interfacial twin boundary phase -- Generalized planar fault energy -- First-principles; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2020.11.056
• Languages: English
• ISSNs: 1005-0302

Abstract

Graphical abstract: Highlights: A new ω-assisted 112 111 β twinning mechanism is proposed. The role of interfacial twin boundary ω phase and its origin are uncovered. A probable microstructure evolution during the 112 111 β twinning is suggested. Abstract: The ω phase is commonly observed in β-Ti alloys and plays a significant role on various properties of β-Ti alloys. Although many results about the role of ω phase on mechanical properties of β-Ti alloys have been derived from theoretical and experimental studies, the role of ω phase on deformation mechanism hitherto remains elusive and deserves to be further studied. In this work, the role played by ω phase during the 112 111 β twinning in Ti-Mo alloys were investigated by first-principles calculations at atomic scale. In the energy favorable interface of ( 112 ) β / ( 10 1 ¯ 0 ) ω, we found that partial dislocations slipping on the successive 10 1 ¯ 0 ω planes of ω phase can lead to the formation of 112 111 β twin nucleus. And the twin nucleus grows inwards ω grain interior through atomic shuffle. Thus, a new twinning mechanism of 112 111 β assisted by ω phase was proposed. Furthermore, our calculations indicated that the appearance of ITB (interfacial twin boundary) ω phase can improve the stability of the symmetrical 112 111 β twin boundary (TB), which can well explain the experimental phenomenon that the ITB ω phase always accompanies the formation of 112 111 β twin. Finally, a probable microstructure evolution sequence was suggested, namely β matrix → β matrix + athermal ω phase → 112 11 1 ¯ β twin → 112 11 1 ¯ β twin + ITB ω phase. Our calculations provide new insights on the role played by ω phase during the twinning process of 112 111 β, which can deepen the understanding on the deformation behaviors of β-Ti alloys.