Phase equilibria and transformations in ternary Mg-rich Mg–Y–Zn alloys

Gröbner, Joachim; Kozlov, Artem; Fang, Xi‐Ya; Geng, Jie; Nie, Jian Feng; Schmid–Fetzer, Rainer

doi:10.1016/j.actamat.2012.05.035

Cited by 193 publications

(86 citation statements)

References 29 publications

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“…The 18R phase is observed predominantly in the as-cast microstructure of Mg-Y-Zn alloys. Both the accumulated experimental evidence and the calculated Mg-YZn phase diagram shown in Figure 27 [224] indicate that 18R is not thermodynamically stable at temperatures below 773 K (500°C); it is gradually replaced by 14H after prolonged heat treatment at 623 K to 773 K (350°C to 500°C).…”

Section: Mg-y-zn Alloysmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,396

519

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Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

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Section: Mg-y-zn Alloysmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,396

519

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“…4) Previously proposed sublattice models in literature for the YZn 5 and H phases are listed in Table 5.…”

Section: H Phasementioning

confidence: 99%

Refinement of Thermodynamic Parameters of the Mg24Y5, W and H Phases in the Mg-Zn-Y System

2015

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The Mg-Zn-Y alloy shows excellent mechanical properties which can be achieved by combining LPSO phase (known as X phase) and an icosahedral quasicrystal phase (I and Z phases) in Mg solid solution (¡ phase). Thermodynamic data for the binary/ternary compounds Mg 24 Y 5 , X, W and H have to be critically assessed to obtain accurate information of three-phase equilibrium in order to understand equilibria among these phases. In this research, we focused on developing CALPHAD (CALculation of PHAse Diagrams) thermodynamic database to evaluate phase diagrams for the Mg-Zn-Y system. Especially thermodynamic models for the Mg 24 Y 5 , W and H phases have been determined based on crystallographic data. Then thermodynamic parameters have been assessed to yield experimental data from EPMA/WDS, SEM, TEM and X-Ray diffraction.

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“…17) The Gibbs energy of LPSO phase, G 0;LPSO Mg:Y:Zn , in MgYZn system is available from thermodynamic Gibbs energy parameter determined by Calphad approach, 17) and G 0;LPSO Mg:Y:Zn is divided into four energies: G c , E grad , E str and E sf , because we consider the LPSO compound phase in this study. Therefore, the energy balance for LPSO single phase provides Z…”

Section: )mentioning

confidence: 99%

Phase-Field Modelling on the Formation Process of LPSO Structure in Mg-Y-Zn System

2015

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It has been proposed that a long-period stacking ordered (LPSO) structure is responsible for the excellent mechanical properties of lightweight alloys of Mg-Y-RE (RE: rare earth elements) system. In this study, the phenomenological simulation model for describing the formation process of the LPSO structure in MgYZn system is constructed by means of the phase-field method. The results obtained are as follows: The proposed phenomenological model is useful for describing the formation process of LPSO structure, where the enrichment of solute elements Zn and Y on stacking fault region induces the growth of the stacking fault itself. This model is able to calculate not only the formation of lamella structure of LPSO phase but also the growth of single stacking fault region in LPSO phase, simultaneously. It is suggested that the lamella spacing of LPSO structure may depend on the initial condition when a LPSO phase nucleates.

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Phase equilibria and transformations in ternary Mg-rich Mg–Y–Zn alloys

Cited by 193 publications

References 29 publications

Precipitation and Hardening in Magnesium Alloys

Precipitation and Hardening in Magnesium Alloys

Refinement of Thermodynamic Parameters of the Mg<sub>24</sub>Y<sub>5</sub>, <i>W</i> and <i>H</i> Phases in the Mg-Zn-Y System

Phase-Field Modelling on the Formation Process of LPSO Structure in Mg-Y-Zn System

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