Quasicrystal strengthened Mg–Zn–Y alloys by extrusion

Singh, Alok; Nakamura, Morihiko; Watanabe, M.; Kato, Akira; Tsai, An‐Pang

doi:10.1016/s1359-6462(03)00305-1

Cited by 217 publications

(94 citation statements)

References 7 publications

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“…The additions of Y to Mg-Zn alloys led to the formation of relatively large particles of a quasicrystalline phase. [90,91] The formation of such quasicrystalline particles does not contribute much to the alloy strength, and therefore, the Mg-Zn-Y alloys are generally extruded to achieve finer magnesium grains for strengthening purpose [92][93][94] (Table II).…”

Section: Phase Equilibria and Precipitationmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,305

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: Phase Equilibria and Precipitationmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,305

519

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“…12) Since a small amount of Zr does not participate in formation of secondary phases, 13) the microstructure and main secondary phases in Mg-Zn-Y-Zr alloys were considered to be similar to the Mg-Zn-Y alloys without Zr addition. 12,14) Rrecent years, interest in the Mg-Zn-Y(-Zr) alloys with quasicrystal at Zn/Y ratio around or over 6 has been growing, 1,[8][9][10][11][12][14][15][16][17][18] because these alloys with the I-phase after going through thermomechanical processing possess excellent yield and ultimate tensile strengths both at room temperature and in a low temperature regime, typically up to 473 K. 1,14,16) In the as-cast Mg-Zn-Y(-Zr) alloys, there plenty of coarse eutectic I-phases locate in the grain boundary region; however, different heat treatment before thermomechanical processing will change the microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effect of Solution Treatment on Microstructure Evolution and Mechanical Properties of Mg-6.0Zn-0.6Y-0.5Zr Alloy Processed by Equal Channel Angular Extrusion

2008

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The effect of solution treatment before equal channel angular extrusion (ECAE) on the evolution of microstructures and mechanical properties in as-cast Mg-6.0Zn-0.6Y-0.5Zr alloy after different ECAE passes has been systematically investigated. The micrographs and tensile results showed that the solution treatment significantly influenced the microstructural evolution, as well as tensile strength and elongation. ECAE processing results in producing finer grain structure both in the as-cast and as-solutionized alloys when the passes increased. However, solution treatment before ECAE provides a significant increase in forming rate of fine recrystallized grains during ECAE at high temperature of 623 K. A fully recrystallized microstructure was observed after 8 passes in the as-solutionized alloy, while it was not finished even after 8 passes in the as-cast alloy. The ductility of as-solutionized alloy is always significantly better than those of the as-cast alloy. However, the strengths of the former are better than those of the later only after the passes beyond 6 passes.

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“…[13][14][15] In this study the thermodynamic parameters for the I phase were taken from Ref. 5) as a stoichiometric compound, however no consideration for the crystal structure.…”

Section: Calphad Thermodynamic Parametersmentioning

confidence: 99%