A simulation study of the shape of β′ precipitates in Mg–Y and Mg–Gd alloys

Liu, H.; Gao, Yipeng; Liu, J.Z.; Zhu, Yuman; Wang, Yixiang; Nie, J. F.

doi:10.1016/j.actamat.2012.09.044

Cited by 171 publications

(59 citation statements)

References 45 publications

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“…Attempts are also made to couple the thermodynamic and kinetic databases with the phase-field method to quantitatively simulate the precipitation behavior and microstructure evolution in Mg-RE alloys [14], which may be useful in further guidance on the practical manufacturing process. However, to realize the computationally aided material design of Mg alloys requires accumulation of large databases of various physical properties, and the experimental analysis on different Mg alloying systems will be a long-lasting work [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation and thermodynamic description of the Mg–Y–Zr system

Cheng

Zhou

et al. 2014

J Mater Sci

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The Mg-Y-Zr system was studied via experimental investigation and thermodynamic modeling. Four diffusion couples and four key alloys of the Mg-Y-Zr system at 500°C were prepared. The phase relations of the Mg-Y-Zr system were investigated by means of X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. No ternary compound was found at 500°C. The solubility of (aZr) in the Mg-Y intermetallics, i.e., Mg 24 Y 5 , Mg 2 Y and MgY, was determined to be negligible. The differential scanning calorimetry measurement was performed on the Mg-Y-Zr alloys to obtain the phase transition temperature. The present thermodynamic calculations of the Mg-Y-Zr system matched well with the experimental data. The presently established Mg-Y-Zr phase diagram can offer a better understanding of the recent processing technique of creep-resistant magnesium alloys.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation and thermodynamic description of the Mg–Y–Zr system

Cheng

Zhou

et al. 2014

J Mater Sci

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“…TEM results also indicate that plate-like β 1 precipitates always forms with a high aspect ratio, and its broad-face {21} β1 parallel to {100} Mg 4567891011. Furthermore, β 1 nucleating within the Mg-matrix is associated with the orthorhombic β′ precipitate phase57, or as self-accommodating β 1 triads511, and heterogeneously along dislocation lines via accommodation of β 1 stress-free transformation strains associated with β 1 formation7891314. Heterogeneous formation is particularly useful in restraining high-temperature creep deformation, because its dynamic nucleation arrests dislocation movement and enhances the creep-resistance of Mg-RE alloys491011.…”

mentioning

confidence: 99%

“…The formation tendencies of β 1 precipitates have been characterized experimentally567891011, and its evolution within Mg matrix and on dislocations studied via phase-field models121314. Despite extensive studies on β 1 phase, basic thermodynamic quantities like β 1 /Mg interfacial energies are yet to be determined unequivocally.…”

mentioning

confidence: 99%

“…Second, a well-developed β 1 plate shares a substantial interfacial-area with the parent Mg-matrix. Thus the interfacial energy, in conjunction with transformation strain energy, will likely determine the plate-like morphology12131415. Therefore, determination of hcp -Mg/β 1 interfacial energies will provide valuable inputs to refine phase field models12131415.…”

mentioning

confidence: 99%

“…Density functional theory (DFT)-based first principles calculations have been used in the past to determine interfacial energies of coherent precipitates in Mg-RE alloys141517. So far, DFT studies on Mg-Nd have largely examined the stability of the β″ (ordered hcp structure5) and the β′ precipitate phases1517; both precipitate phases form at early stages prior to β 1 precipitation.…”

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confidence: 99%

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Interfacial structures and energetics of the strengthening precipitate phase in creep-resistant Mg-Nd-based alloys

Choudhuri

Banerjee

Srinivasan

2017

Sci Rep

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The extraordinary creep-resistance of Mg-Nd-based alloys can be correlated to the formation of nanoscale-platelets of β 1 -Mg 3 Nd precipitates, that grow along 〈1120〉 Mg in bulk hcp-Mg and on dislocation lines. The growth kinetics of β 1 is sluggish even at high temperatures, and presumably occurs via vacancy migration. However, the rationale for the high-temperature stability of precipitatematrix interfaces and observed growth direction is unknown, and may likely be related to the interfacial structure and excess energy. Therefore, we study two interfaces-{112} β1 /{1100} Mg and {111} β1 /{1120} Mgthat are commensurate with β 1 /hcp-Mg orientation relationship via first principles calculations. We find that β 1 acquires plate-like morphology to reduce small lattice strain via the formation of energetically favorable {112} β1 /{1100} Mg interfaces, and predict that β 1 grows along 〈1120〉 Mg on dislocation lines due to the migration of metastable {111} β1 /{1120} Mg . Furthermore, electronic charge distribution of the two interfaces studied here indicated that interfacial-energy of coherent precipitates is sensitive to the population of distorted lattice sites, and their spatial extent in the vicinity of interfaces. Our results have implications for alloy design as they suggest that formation of β 1 -like precipitates in the hcp-Mg matrix will require well-bonded coherent interface along precipitate broad-faces, while simultaneously destabilizing other interfaces.Magnesium (Mg) alloys have tremendous potential as structural materials for automotive applications in engine block, transmission parts due to their lightweight. The concomitant fuel savings is however, thwarted by their unfavorable creep strength 1-4 . Mg-rare earth (RE) alloys are exceptions with demonstrated excellent creep resistance 1-3 . Their superior creep properties are correlated to the formation of high volume fractions of strengthening precipitates based on RE intermetallic compounds 4,5 . However, the scarcity and high cost of RE elements limits the development of creep-resistant Mg-RE alloys. This work is motivated by gaining an atomistic understanding of commonly found strengthening precipitates in creep-resistant Mg-RE alloys, and inform Mg-alloy design approaches by providing energetics and bonding characteristics associated with their presence within the hcp-Mg matrix. Therefore, we have investigated the structure of interface between intermetallic precipitate phase β 1 (an ordered cubic structure) and hcp-Mg. This precipitate typically forms in Mg-Nd-based alloys like Mg-Nd, Mg-Nd-Y and Mg-Nd-Y-Zr, e.g. commercial WE43 and WE54 5-7 . The coherent β 1 phase has a plate-like morphology, and shares an (0001) Mg [5][6][7][8][9][10][11][12] . TEM results also indicate that plate-like β 1 precipitates always forms with a high aspect ratio, and its broad-face {211} β1 parallel to {1100} Mg 4-11 . Furthermore, β 1 nucleating within the Mg-matrix is associated with the orthorhombic β ′ precipitate phase 5,7 , or as self-accommodating β 1 tr...

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Precipitation in Mg–Nd–Y–Zr–Ca Alloy during Isothermal Aging: A Comprehensive Atomic‐Scaled Study by Means of HAADF‐STEM

Zheng

Luo

et al. 2016

Adv Eng Mater

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This paper investigates into the precipitation behavior of Mg-2Nd-1Y-0.1Zr-0.1Ca (wt%) alloy during isothermal aging at 225 C, using atomic-scale HAADF-STEM. The precipitation sequence in Mg-Nd-Y-Zr-Ca is identified as follows:From an engineering point of view, the atomic-size precipitates that distribute uniformly have a significant strengthening effect. In addition, the present study discusses three findings concerning the novel structures observed in the alloy: two types of interaction between needle-like precipitates are observed; the previously reported b 00 structure is doubted according to the analysis of the defects characterized from [11 20] Mg ; calcium is observed to be enriched in b1 precipitates and along grain boundaries.

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A simulation study of the shape of β′ precipitates in Mg–Y and Mg–Gd alloys

Cited by 171 publications

References 45 publications

Experimental investigation and thermodynamic description of the Mg–Y–Zr system

Experimental investigation and thermodynamic description of the Mg–Y–Zr system

Interfacial structures and energetics of the strengthening precipitate phase in creep-resistant Mg-Nd-based alloys

Precipitation in Mg–Nd–Y–Zr–Ca Alloy during Isothermal Aging: A Comprehensive Atomic‐Scaled Study by Means of HAADF‐STEM

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