Hcp → ω phase transition mechanisms in shocked zirconium: A machine learning based atomic simulation study. (1st January 2019)

• Record Type: Journal Article
• Authors: Zong, Hongxiang; Luo, Yufei; Ding, Xiangdong; Lookman, Turab; Ackland, Graeme J.
• Is Part Of: Acta materialia. Volume 162(2019)
• Page Start: 126
• Page End: 135
• Publication Date: 2019-01-01
• Subjects: Shock compression -- Phase transition -- Zirconium -- Orientation relationship; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.09.067
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: There has been much controversy over the behavior of zirconium under shock strong enough to cause the pressure-induced hcp → ω phase transformation. Due to the short time- and length scales involved, direct measurements of the microstructure are extremely challenging. We have performed molecular dynamics simulations to investigate this issue, with Zr described by a machine-learned interatomic potential. Two different orientation relationships (ORs) between the hcp and ω phases are observed under shock driven conditions. Unlike the case with Ti that is in the same group, the ORs between the hcp and ω phases show less anisotropic phase transition sensitivity and in most cases follow the Silcock relationship with ( 0001 ) α | | ( 1 2 ¯ 10 ) ω . Furthermore, we find that the α→ ω transformation in shocked Zr occurs via an intermediate metastable bcc structure during the loading process, whereas no such intermediate is found during the reverse ω→α transition when the shock releases. Graphical abstract: Image 1