First Principles Calculations of Solute Ordering in Mg&amp;ndash;Zn&amp;ndash;Y Alloys

Yamamoto, Yosuke; Sakamoto, Yuichi; Masaki, Yoshihiro; Nishitani, Shigeto R.

doi:10.2320/matertrans.mi201207

Cited by 3 publications

(4 citation statements)

References 14 publications

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“…In a previous paper, 4) we reported negative data for the solute-ordering-initiated scenario. For investigating the solute ordering, we checked the interaction energies of many configurations between solute atoms, between solute pairs, and between stacking-faults and solute atoms.…”

Section: Introductionmentioning

confidence: 78%

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First Principles Calculations of Solute Sweeping and Stacking Faults in Mg-Zn-Y Alloy

et al. 2015

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The formation mechanism of the long-period stacking-ordered (LPSO) structure of a Mg-Zn-Y alloy was investigated through energy assessments using first-principles calculations. The solute atoms are swept out from stacking fault regions because of their repulsive interaction with precipitated L1 2 clusters. The swept-out solute atoms are condensed a few layers away from the stacking-fault regions and accelerate the introduction of other stacking faults. A new scenario in the formation of the LPSO structure is proposed.

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Section: Introductionmentioning

confidence: 78%

“…35) Two factors play a role in the formation mechanism: stacking faults and solute atoms. Two simple scenarios have immediately been proposed: 4) Stacking-fault-initiated scenario…”

Section: Introductionmentioning

confidence: 99%

First Principles Calculations of Solute Sweeping and Stacking Faults in Mg-Zn-Y Alloy

et al. 2015

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“…According to Nishitani et al, Zn-Y atomic pair is more stable than Mg-Zn or Mg-Y pair. 14) In the model, 2H-type Mg matrix is extended to 4 © 4 © 3 and adjoining two Mg atoms are replaced by Zn and Y atoms (Fig. 4(a)).…”

Section: Resultsmentioning

confidence: 99%

Local Strain Fields of LPSO in Mg-Based Ternary Alloys

et al. 2015

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L1 2 -type TM 6 RE 8 clusters are distributed in enriched layers of LPSO (long period stacking ordered structure), and shrink in the [0001] Mg direction. The growth mechanism of LPSOs was investigated from the viewpoint of a local strain field. The strength of out-of plane normal strain of the enriched layer varied with the average radius of solute elements in the layer. The first principle calculation showed that there is a relationship between the average atomic radius of solute elements and the structural relaxation in the clusters. Zn conclusion, it is suggested that the difference of average atomic radius between Mg and solute elements controls the degree of the cluster shrinkage by the displacement of the solute elements, and that it is the dominant factor giving rise to the out-of plane normal strains of the enrichment layers.

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“…Clustering of solute elements and the introduction of the I 2 -SF are essential events for formation of the LPSO structure. Recent studies have suggested two possible formation processes of the LPSO structures; one driven by the introduction of the I 2 -SF, and the other driven by spinodal-like phase separation which involves clustering of solute atoms (Yamamoto et al, 2013;Umebayashi et al, 2014;Okuda et al, 2015Okuda et al, , 2017Egami et al, under review). Okuda et al investigated precipitation processes of the LPSO phase from the amorphous Mg-Zn-RE alloys in the quenched ribbon sample by in-situ synchrotron X-ray observations (Okuda et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Direct Observations of Precursor Short-Range Order Clusters of Solute Atoms in a LPSO-Forming Mg-Zn-Gd Ternary Alloy

2019

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We have investigated short-range order (SRO) clusters of solute atoms in a Mg 97 Zn 1 Gd 2 alloy which forms a long-period stacking/order (LPSO) phase, based on aberration-corrected scanning transmission electron microscopy (STEM) observations and first-principles calculations. High-angle annular dark-field (HAADF) STEM provides directly the individual Gd atom positions through significant atomic-number dependent Z-contrast, and their averaged image-processing have immediately shown up the representative SRO-Gd configurations being in favor of the second-nearest networks in the hcp-Mg structure. Interestingly, Zn atoms seem to be essentially placed at the particular sites within the SRO-Gd configurations to form D0 19-like ZnGd 3 clusters, a validity of which are verified by STEM image simulations and first-principles calculations. These D0 19-like ZnGd 3 clusters in the hcp-Mg matrix are likely to be a precursor sub-structure to the L1 2-type Zn 6 Gd 8 clusters that are embedded in the local fcc layers in the LPSO structure. In fact, we find that these D0 19-like ZnGd 3 clusters seem to form a layered atmosphere prior to the LPSO formation, providing an important clue on how the LPSO phases nucleate and grow.

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First Principles Calculations of Solute Ordering in Mg–Zn–Y Alloys

Cited by 3 publications

References 14 publications

First Principles Calculations of Solute Sweeping and Stacking Faults in Mg-Zn-Y Alloy

First Principles Calculations of Solute Sweeping and Stacking Faults in Mg-Zn-Y Alloy

Local Strain Fields of LPSO in Mg-Based Ternary Alloys

Direct Observations of Precursor Short-Range Order Clusters of Solute Atoms in a LPSO-Forming Mg-Zn-Gd Ternary Alloy

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