Study of Mg–Gd–Zn–Zr alloys with long period stacking ordered structures

Zhang, Jinshan; Zhang, Wenbo; Bian, Lichun; Cheng, Weili; Niu, Xiaofeng; Xu, Chunxiang; Wu, Shaojie

doi:10.1016/j.msea.2013.07.049

Cited by 61 publications

(26 citation statements)

References 22 publications

(26 reference statements)

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“…According to the XRD patterns (Fig. 2) of the alloys A and C, the eutectic phases are confirmed as (Mg,Zn) 3 Gd phases, which is consistent with previous studies [4,5] . The morphologies of α-Mg grains and eutectic phases of the alloys change with different Li content.…”

Section: Methodssupporting

confidence: 91%

“…Based on the analyses mentioned above and the XRD peaks in Fig. 2, both the coarse continuous phase and lamellar phase were identified as 14H-LPSO structure phases, which were in agreement with previous investigations [4][5] . With the addition of Li, the microstructure of solid-solution treated MgGd 3 Zn 1 alloy changed significantly.…”

Section: Microstructures Of As-cast Alloys a B C And Dsupporting

confidence: 90%

“…Nevertheless, as a kind of second phase, the coarse block-like LPSO phase usually precipitates at grain boundaries during traditional solidification or subsequent solid solution treatment [4][5] , which was reported to cause a decrease in strength [6][7] . Recently, various processes, such as extrusion [8][9] , friction stir processing (FSP) [10][11] and severe plastic deformation [12][13] , have been applied to achieve refined microstructure and enhanced mechanical properties.…”

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confidence: 99%

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Effect of Li on formation of long period stacking ordered phases and mechanical properties of Mg-Gd-Zn alloy

et al. 2016

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M g-Re-Zn alloys have attracted increasing attention due to their superior mechanical properties, attributing to the formation of lamellar long period stacking ordered (LPSO) phases within an α-Mg matrix [1][2][3] . Nevertheless, as a kind of second phase, the coarse block-like LPSO phase usually precipitates at grain boundaries during traditional solidification or subsequent solid solution treatment [4][5] , which was reported to cause a decrease in strength [6][7] . Recently, various processes, such as extrusion [8][9] , friction stir processing (FSP) [10][11] and severe plastic deformation [12][13] , have been applied to achieve refined microstructure and enhanced mechanical properties. However, the coarse LPSO phase with excellent plasticity is hard to be broken. What's worse, all these methods will raise the production cost. Hence, there is a great importance to develop an effective and simple technology to decrease the detrimental influence of the coarse second phase.Alloying treatment is a simple and economical method to improve the properties of alloys. To further improve the Abstract: Alloys with composition of Mg 96-x Gd 3 Zn 1 Li x (at.%) (x=0, 2, 4, and 6) were prepared by conventional casting. The microstructures of these alloys under as-cast and solid-solution conditions have been observed, and the mechanical properties were investigated. The results showed that Li is an effective element to refine the grains and break the eutectic networks in as-cast MgGd 3 Zn 1 alloy. During solid solution treatment, these broken eutectic networks are spheroidized and highly dispersed. In addition, plentiful lamellar long period stacking ordered (LPSO) phases are precipitated in an α-Mg matrix when the Li addition is not more than 4%. Solid-solution treated Mg 92 Gd 3 Zn 1 Li 4 alloy exhibits an optimal ultimate tensile strength (UTS) of 226 MPa and elongation of 5.8%. The strength of MgGd 3 Zn 1 alloy is improved significantly, meanwhile, the toughness is apparently increased. properties, heat treatment is usually adopted following the alloying treatment, which gives another simple and effective property improving method. Therefore, a proper combination of alloying and heat treatment is needed to obtain optimal mechanical properties. It has been demonstrated that Mn, Sr and Li are effective elements to modify the size and morphology of the second phases in cast aluminum alloys [14][15][16] . After heat treatment, the modified A380 aluminum alloy shows a significant improvement in tensile properties [17] . The method and principle of alloying and heat treatment for magnesium and aluminum alloys are similar. So, is it possible that the addition of these elements could modify the eutectic networks of as-cast Mg-Re-Zn alloy or turn the coarse second phase into less harmful forms during the following heat treatment? Furthermore, the addition of Li can decrease the lattice constant ratios (c/a) through the substitution of Mg atoms by Li atoms, which will improve the ductility [18][19][20] . The reduction of the atomic...

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Section: Methodssupporting

confidence: 91%

Section: Microstructures Of As-cast Alloys a B C And Dsupporting

confidence: 90%

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confidence: 99%

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Effect of Li on formation of long period stacking ordered phases and mechanical properties of Mg-Gd-Zn alloy

et al. 2016

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“…The alloying elements can strengthen magnesium alloys by second phase strengthening, solute solution strengthening, and precipitation strengthening [6,7]. Among various elements, heavy rare earth (HRE) elements, such as Gd and Y, are the most effective because they introduce severe lattice distortion when dissolved in α-Mg solid solution, and their solubility limits in α-Mg decline sharply with decreasing temperatures, which causes an obvious age-hardening response [8,9]. Moreover, by adding Zn and HRE elements simultaneously, a kind of novel long period stacking ordered (LPSO) structure is formed, which exhibits an extraordinary strengthening effect, especially in hot extruded or rolled Mg-RE-Zn alloys [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Preparation, Microstructure Evolutions, and Mechanical Property of an Ultra-Fine Grained Mg-10Gd-4Y-1.5Zn-0.5Zr Alloy

Liu

Bai

et al. 2017

Metals

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Abstract:In this work, the microstructural evolutions and mechanical properties of an as-cast Mg-10Gd-4Y-1.5Zn-0.5Zr (wt %) alloy during successive multi-pass equal channel angular pressing (ECAP) were systematically investigated by X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, and compression test. The obtained results show that the microstructure of as-cast alloy consists of α-Mg grains, Mg 3 Gd island phase, few Y-rich particles, and lamellar 14H LPSO (long period stacking ordered) phase located at the grain boundaries. During ECAP, the Mg 3 Gd-type phase is crushed and refined gradually. However, the refined Mg 3 Gd particles are not distributed uniformly in the matrix, but still aggregated at the interdendritic area. The 14H phase becomes kinked during the early passes of ECAP and then broken at the kinking bands with more severe deformation. Dynamic recrystallization of α-Mg is activated during ECAP, and their average diameter decreases to around 1 µm, which is stabilized in spite of increasing ECAP passes. Moreover, nano-scale γ phases were dynamically precipitated in 16p ECAP alloy. Compression tests indicate that 16p ECAP alloy exhibits excellent mechanical property with compressive strength of 548 MPa and fracture strain of 19.1%. The significant improvement for both strength and ductility of deformed alloy could be ascribed to dynamic recrystallization (DRX) grains, refined Mg 3 Gd-type and 14H particles, and dynamically precipitated γ plates.

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“…The development of heat-treatable alloys whereby fine precipitates or local clustering of solute atoms together with the formation of different types of long periodic stacking ordered structures (LPSOs) contribute significantly to the strengthening as well as retaining or imparting some measure of improved ductility to the matrix. [6][7][8][9][10][11][12][13][14][15][16][17][18] Some commonly studied LPSOs include…”

Section: Introductionmentioning

confidence: 99%

Solid-Solution Hardening in Mg-Gd-TM (TM = Ag, Zn, and Zr) Alloys: An Integrated Density Functional Theory and Electron Work Function Study

Wang

Shang

Wang

et al. 2015

JOM

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The current work aims to reveal the effects of solute atoms (TM = Ag, Zn, and Zr) on the age hardening of Mg-Gd-based alloys via the density functional theory and electron work function (EWF) approaches. The 10H LPSO phases of Mg-Gd-TM alloys are selected as the model case due to the improved strength and ductility such long periodic stacking ordered precipitates (LPSOs) offer. The CALPHAD-modeling method is applied to predict the EWF in the ternary Mg-Gd-TM alloys. The obtained EWFs of these Mg alloys are shown to match well with previous experimental and theoretical results. Moreover, the variation of EWF in the ternary Mg-Gd-TM alloys is attributed to the structure contribution [i.e., the formation of face-centered cubic (fcc)-type fault layers] and the chemical effect of solute atoms (i.e., electron redistributions). With the knowledge of bonding charge density between the solute and solvent atoms, the present work provides insight into the correlations between the EWF and hardness of Mg-Gd-TM alloys.

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Study of Mg–Gd–Zn–Zr alloys with long period stacking ordered structures

Cited by 61 publications

References 22 publications

Effect of Li on formation of long period stacking ordered phases and mechanical properties of Mg-Gd-Zn alloy

Effect of Li on formation of long period stacking ordered phases and mechanical properties of Mg-Gd-Zn alloy

Preparation, Microstructure Evolutions, and Mechanical Property of an Ultra-Fine Grained Mg-10Gd-4Y-1.5Zn-0.5Zr Alloy

Solid-Solution Hardening in Mg-Gd-TM (TM = Ag, Zn, and Zr) Alloys: An Integrated Density Functional Theory and Electron Work Function Study

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