On the slip and twinning mechanisms on first order pyramidal plane of magnesium: Molecular dynamics simulations and first principal studies

Reza Namakian , George Z. Voyiadjis , Piotr Kwaśniak

Abstract

Molecular dynamics simulations and first-principles calculations are carried out on first order pyramidal plane (π1) of magnesium to study both compression twinning (CTW) and dislocation slip. To this end, a generalized stacking fault energy analysis is employed on dense (π1D) and loose spaced (π1L) π1 planes. The crystal shearing resistance is extracted by using a minimum-energy path (MEP) finder called the nudged elastic band (NEB) method. The MEP regarding 1¯012101¯1π1L slip system shows that the unfaulted crystal structure is recovered in the middle of the path with non-straight and pronounced curved slip trajectories. Besides, it will be revealed that metastable configurations on the half of the MEP for 1¯012101¯1π1L slip system are indeed related to a dissociated 〈c + a〉 extended dislocation of loose pyramidal-I 〈c + a〉 slip, 1/31¯1¯23101¯1π1L . Also, after extracting the dissociation mechanism related to this dislocation, it will be shown that loose pyramidal-I 〈c + a〉 slip can involve shuffling. Moreover, the MEP for dense pyramidal-I 〈a〉 slip, 1/31¯21¯0101¯1π1D , shows transmutation of this slip into CTW in the middle of the path. This transmutation process will be further examined on CTW growth, and it will be demonstrated that this CTW mechanism is energetically more favorable compared to other twinning mechanisms.

Author Reza Namakian - Louisiana State University
Reza Namakian,,
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, George Z. Voyiadjis - Louisiana State University
George Z. Voyiadjis,,
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, Piotr Kwaśniak (FMSE / DMD)
Piotr Kwaśniak,,
- Division of Materials Design
Journal seriesMaterials & Design, [Materials and Design], ISSN 0264-1275, e-ISSN 1873-4197, [0261-3069]
Issue year2020
Vol191
Pages1-19
Publication size in sheets0.9
Keywords in EnglishMagnesium; First order pyramidal slip; Contraction twinning; First-principles calculations; Molecular dynamics simulations
ASJC Classification2210 Mechanical Engineering; 2211 Mechanics of Materials; 2500 General Materials Science
DOIDOI:10.1016/j.matdes.2020.108648
URL https://reader.elsevier.com/reader/sd/pii/S0264127520301829?token=906B41B3D55CF5D282FCAE25B7CE140AD7DD5081BCD81BECD86B017625EC18E7BF26D7CFA29265FD54FEF1429F337739
Languageen angielski
File
1-s2.0-S0264127520301829-main.pdf 7.29 MB
Score (nominal)140
Score sourcejournalList
ScoreMinisterial score = 140.0, 22-07-2020, ArticleFromJournal
Publication indicators Scopus Citations = 0; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 2.424; WoS Impact Factor: 2018 = 5.77 (2) - 2018=5.83 (5)
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