Transitions in mechanical behavior and in deformation mechanisms enhance the strength and ductility of Mg-3Gd

Xuan Luo, Zongqiang Feng, Tianbo Yu, Junqian Luo, Tianlin Huang, Guilin Wu, Niels Hansen, Xiaoxu Huang*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Samples of Mg-3Gd (wt.%) were prepared by accumulative roll-bonding followed by annealing at different temperatures to produce samples with average grain sizes ranging from 3.3 µm to 114 µm. The samples were tensile tested at room temperature to characterize their strength and ductility, both of which were found to be significantly affected by transitions in mechanical behavior and deformation mechanisms. These transitions occurred with decreasing grain size and are described by: (i) a transition in the mechanical behavior from continuous flow to discontinuous flow associated with a yield point phenomenon, and (ii) a transition in the deformation mechanisms from 〈a〉 slip and twinning to 〈a〉 and 〈c + a〉 slips. The dislocation structures and deformation twins in the tensile samples have been characterized by transmission electron microscopy and electron backscatter diffraction, respectively. Dislocations of 〈a〉 and 〈c + a〉 type were identified based on two-beam diffraction contrast experiments. The results reveal that 〈a〉 dislocations and tension twins dominate in the samples with grain sizes larger than 10 µm, while 〈a〉 and 〈c + a〉 dislocations dominate in the samples with grain sizes smaller than 5 µm. In parallel, a consistent trend for both the strength and ductility to increase with decreasing grain size is observed. The appearance of a yield point phenomenon at small grain sizes has a significant effect on both strength and ductility, illustrated by an increase in boundary (Hall–Petch) strengthening and an increase in the total elongation to 36.6%. These results demonstrated a positive effect of a superposition of the transitions on both the strength and ductility of Mg-3Gd.
Original languageEnglish
JournalActa Materialia
Volume183
Pages (from-to)398-407
ISSN1359-6454
DOIs
Publication statusPublished - 2020

Bibliographical note

GA no. 788567

Keywords

  • Mg-3Gd alloy
  • Grain size
  • Hall–Petch relationship
  • <c+a> dislocations
  • Twinning

Cite this

Luo, Xuan ; Feng, Zongqiang ; Yu, Tianbo ; Luo, Junqian ; Huang, Tianlin ; Wu, Guilin ; Hansen, Niels ; Huang, Xiaoxu. / Transitions in mechanical behavior and in deformation mechanisms enhance the strength and ductility of Mg-3Gd. In: Acta Materialia. 2020 ; Vol. 183. pp. 398-407.
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title = "Transitions in mechanical behavior and in deformation mechanisms enhance the strength and ductility of Mg-3Gd",
abstract = "Samples of Mg-3Gd (wt.{\%}) were prepared by accumulative roll-bonding followed by annealing at different temperatures to produce samples with average grain sizes ranging from 3.3 µm to 114 µm. The samples were tensile tested at room temperature to characterize their strength and ductility, both of which were found to be significantly affected by transitions in mechanical behavior and deformation mechanisms. These transitions occurred with decreasing grain size and are described by: (i) a transition in the mechanical behavior from continuous flow to discontinuous flow associated with a yield point phenomenon, and (ii) a transition in the deformation mechanisms from 〈a〉 slip and twinning to 〈a〉 and 〈c + a〉 slips. The dislocation structures and deformation twins in the tensile samples have been characterized by transmission electron microscopy and electron backscatter diffraction, respectively. Dislocations of 〈a〉 and 〈c + a〉 type were identified based on two-beam diffraction contrast experiments. The results reveal that 〈a〉 dislocations and tension twins dominate in the samples with grain sizes larger than 10 µm, while 〈a〉 and 〈c + a〉 dislocations dominate in the samples with grain sizes smaller than 5 µm. In parallel, a consistent trend for both the strength and ductility to increase with decreasing grain size is observed. The appearance of a yield point phenomenon at small grain sizes has a significant effect on both strength and ductility, illustrated by an increase in boundary (Hall–Petch) strengthening and an increase in the total elongation to 36.6{\%}. These results demonstrated a positive effect of a superposition of the transitions on both the strength and ductility of Mg-3Gd.",
keywords = "Mg-3Gd alloy, Grain size, Hall–Petch relationship, <c+a> dislocations, Twinning",
author = "Xuan Luo and Zongqiang Feng and Tianbo Yu and Junqian Luo and Tianlin Huang and Guilin Wu and Niels Hansen and Xiaoxu Huang",
note = "GA no. 788567",
year = "2020",
doi = "10.1016/j.actamat.2019.11.034",
language = "English",
volume = "183",
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journal = "Acta Materialia",
issn = "1359-6454",
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Transitions in mechanical behavior and in deformation mechanisms enhance the strength and ductility of Mg-3Gd. / Luo, Xuan; Feng, Zongqiang; Yu, Tianbo; Luo, Junqian; Huang, Tianlin; Wu, Guilin; Hansen, Niels; Huang, Xiaoxu.

In: Acta Materialia, Vol. 183, 2020, p. 398-407.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Transitions in mechanical behavior and in deformation mechanisms enhance the strength and ductility of Mg-3Gd

AU - Luo, Xuan

AU - Feng, Zongqiang

AU - Yu, Tianbo

AU - Luo, Junqian

AU - Huang, Tianlin

AU - Wu, Guilin

AU - Hansen, Niels

AU - Huang, Xiaoxu

N1 - GA no. 788567

PY - 2020

Y1 - 2020

N2 - Samples of Mg-3Gd (wt.%) were prepared by accumulative roll-bonding followed by annealing at different temperatures to produce samples with average grain sizes ranging from 3.3 µm to 114 µm. The samples were tensile tested at room temperature to characterize their strength and ductility, both of which were found to be significantly affected by transitions in mechanical behavior and deformation mechanisms. These transitions occurred with decreasing grain size and are described by: (i) a transition in the mechanical behavior from continuous flow to discontinuous flow associated with a yield point phenomenon, and (ii) a transition in the deformation mechanisms from 〈a〉 slip and twinning to 〈a〉 and 〈c + a〉 slips. The dislocation structures and deformation twins in the tensile samples have been characterized by transmission electron microscopy and electron backscatter diffraction, respectively. Dislocations of 〈a〉 and 〈c + a〉 type were identified based on two-beam diffraction contrast experiments. The results reveal that 〈a〉 dislocations and tension twins dominate in the samples with grain sizes larger than 10 µm, while 〈a〉 and 〈c + a〉 dislocations dominate in the samples with grain sizes smaller than 5 µm. In parallel, a consistent trend for both the strength and ductility to increase with decreasing grain size is observed. The appearance of a yield point phenomenon at small grain sizes has a significant effect on both strength and ductility, illustrated by an increase in boundary (Hall–Petch) strengthening and an increase in the total elongation to 36.6%. These results demonstrated a positive effect of a superposition of the transitions on both the strength and ductility of Mg-3Gd.

AB - Samples of Mg-3Gd (wt.%) were prepared by accumulative roll-bonding followed by annealing at different temperatures to produce samples with average grain sizes ranging from 3.3 µm to 114 µm. The samples were tensile tested at room temperature to characterize their strength and ductility, both of which were found to be significantly affected by transitions in mechanical behavior and deformation mechanisms. These transitions occurred with decreasing grain size and are described by: (i) a transition in the mechanical behavior from continuous flow to discontinuous flow associated with a yield point phenomenon, and (ii) a transition in the deformation mechanisms from 〈a〉 slip and twinning to 〈a〉 and 〈c + a〉 slips. The dislocation structures and deformation twins in the tensile samples have been characterized by transmission electron microscopy and electron backscatter diffraction, respectively. Dislocations of 〈a〉 and 〈c + a〉 type were identified based on two-beam diffraction contrast experiments. The results reveal that 〈a〉 dislocations and tension twins dominate in the samples with grain sizes larger than 10 µm, while 〈a〉 and 〈c + a〉 dislocations dominate in the samples with grain sizes smaller than 5 µm. In parallel, a consistent trend for both the strength and ductility to increase with decreasing grain size is observed. The appearance of a yield point phenomenon at small grain sizes has a significant effect on both strength and ductility, illustrated by an increase in boundary (Hall–Petch) strengthening and an increase in the total elongation to 36.6%. These results demonstrated a positive effect of a superposition of the transitions on both the strength and ductility of Mg-3Gd.

KW - Mg-3Gd alloy

KW - Grain size

KW - Hall–Petch relationship

KW - <c+a> dislocations

KW - Twinning

U2 - 10.1016/j.actamat.2019.11.034

DO - 10.1016/j.actamat.2019.11.034

M3 - Journal article

VL - 183

SP - 398

EP - 407

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

ER -