Fabrication of extraordinary high-strength magnesium alloy by hot extrusion

Homma, Tomoyuki; Kunito, N.; Kamado, Shigeharu

doi:10.1016/j.scriptamat.2009.06.003

Cited by 522 publications

(186 citation statements)

References 24 publications

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“…But around years 2007 to 2009, the yield strength of magnesium alloys approached 320 MPa for casting alloys [235] and 475 MPa for extrusion alloys. [202] A similar or even faster pace is expected in the development of highstrength magnesium alloys if the level of magnesium research activities enjoyed over the past 12 years can be maintained in the future. The precipitation hardening phenomenon in aluminum alloys was discovered accidentally by Alfred Wilm in 1906, [273][274][275] and the strength of aluminum alloys made at that time was compatible to that of precipitation-hardenable magnesium alloys in year 2000.…”

Section: Microstructural Design For Higher Strengthmentioning

confidence: 95%

“…[201] However, an impressively high value of 473 MPa has been achieved for the 0.2 pct proof strength in an extruded and aged Mg-1.8Gd-1.8Y-0.7Zn-0.2Zr (at. pct) or Mg-10Gd-5.7Y-1.6Zn-0.7Zr (wt pct) alloy [202] (Table II). The remarkable age-hardening response achieved in the Mg-Gd-Y alloys is attributable to a dense distribution of precipitates in the microstructure.…”

Section: Mg-gd-y-based Alloysmentioning

confidence: 99%

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Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,394

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: Microstructural Design For Higher Strengthmentioning

confidence: 95%

Section: Mg-gd-y-based Alloysmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,394

519

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“…Since the reported magnesium alloys listed in Table 1 include alloying elements to suppress grain growth and are fabricated by extrusion or ECAP possesses, they possess a small grain size of below 15 μm. Among them, the alloy which shows higher UTS than the Mg-Sc sample aged for 18 ks has a very small grain size of 1.1 μm 24) . The present Mg-Sc alloy has much larger grain size of 40.7 μm (α phase) and 33.1 μm (β phase) than the reported magnesium alloys.…”

Section: Tensile Propertiesmentioning

confidence: 99%

Aging Effect of Mg-Sc Alloy with α+β Two-Phase Microstructure

et al. 2016

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Mg-20.5 at% Sc alloy with hcp (α)+bcc (β) two-phase was investigated to understand the effects of aging treatment at 473 K on microstructure, hardness and tensile properties. A Mg-Sc alloy ingot was prepared by induction melting in an Ar atmosphere, and then hot rolled at 873 K followed by cold rolling into a sheet. The rolled specimens were annealed at 873 K to obtain an α+β two-phase microstructure. The annealed specimens were then aged at 473 K for various time. Vickers hardness of the α+β two-phase alloy drastically increased after a certain incubation time and then reached a maximum hardness of 142.8 HV. The incubation time of the Mg-20.5 at% Sc alloy with the α+β two-phase was longer than that of the same alloy with a β single-phase. Ultimate tensile strength (UTS) and elongation of the as-annealed specimen were 280 MPa and 28.2%, respectively. Meanwhile, the specimen aged at 473 K for 14.4 ks showed a UTS of 357 MPa and an elongation of over 12%. The specimen aged for 18 ks showed a higher UTS of 465 MPa, while keeping a better elongation of 6.9%. The age hardening of the MgSc alloys was found to be due to the precipitation of very ne α phase in β phase.

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“…Fine Mg 2 Si particles contribute to the improvement in the mechanical behavior of the alloys. On the other hand, alloys with coarse Mg 2 Si particles exhibit worse mechanical properties [5,6]. In general, the material matrix would be fragmented seriously by large primary Mg 2 Si and dendritic eutectic Mg 2 Si.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Behavior of Mg-0.5Si-xSn Alloys

Yang

et al. 2017

Archives of Foundry Engineering

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Mg-0.5Si-xSn (x=0.95, 2.9, 5.02wt.%) alloys were cast and extruded at 593K (320 o C) with an extrusion ratio of 25. The microstructure and mechanical properties of as-cast and extruded test alloys were investigated by OM, SEM, XRD and tensile tests. The experimental results indicate that the microstructure of the Mg-0.5Si-xSn alloys consists of primary α-Mg dendrites and an interdendritic eutectic containing α-Mg, Mg 2 Si and Mg 2 Sn. There is no coarse primary Mg 2 Si phase in the test alloys due to low Si content. With the increase in the Sn content, the Mg 2 Si phase was refined. The shape of Mg 2 Si phase was changed from branch to short bar, and the size of them were reduced. The ultimate tensile strength and yield strength of Mg-0.52Si-2.9Sn alloy at the temperature of 473K (200 o C) reach 133MPa and 112MPa respectively. Refined eutectic Mg 2 Si phase and dispersed Mg 2 Sn phase with good elevated temperature stability are beneficial to improve the elevated temperature performance of the alloys. However, with the excess addition of Sn, large block-like Mg 2 Sn appears around the grain boundary leading to lower mechanical properties.

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Fabrication of extraordinary high-strength magnesium alloy by hot extrusion

Cited by 522 publications

References 24 publications

Precipitation and Hardening in Magnesium Alloys

Precipitation and Hardening in Magnesium Alloys

Aging Effect of Mg-Sc Alloy with α+β Two-Phase Microstructure

Microstructure and Mechanical Behavior of Mg-0.5Si-xSn Alloys

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