Ultrahigh strength wrought Mg alloys developed in Harbin Institute of Technology

 

M.Y. Zheng


School of Materials Science and Engineering,Harbin Institute of Technology, Harbin, China


 30 th of november

at 12-40 p.m.

ap. B-607

There is a growing need for ultrahigh-strength wrought Mg alloys in automotive and aerospace industries.In this presentation, three series of ultrahigh strength Mg alloys developed in Harbin Institute of Technology (HIT), China are introduced.

Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt%)alloyextrusion rods and rollingsheets with bothultra-highstrengthandsuperiorductility is developed by direct-chill casting, hot deformationand ageing treatment. The extrudedMg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt%)alloy after T5 treatment exhibits a tensile yield strength (TYS), an ultimate tensile strength (UTS) and an elongation to failure of 462MPa, 520 MPa and 10.2%, respectively, which is mainly attributed to the precipitation of fineβphases, andthe formation of dense nanostacking faults (SFs) and long period stacking ordered(LPSO) phase.The commercialization of the Mg-Gd-Y-Zn-Zr alloys is discussed.

A new ultrahigh-strength W phase (Mg3Y2Zn3) containing Mg-10.3Zn-6.4Y-0.4Zr- 0.5Ca (wt.%) alloy with medium RE content has been fabricated through conventional casting and indirect extrusion. The as-extruded alloy exhibits ultimate tensile strength of 466 MPa, tensile yield strength of 447 MPa and elongation to failure of 4.7%.Large number of nano W phase dynamically precipitated during extrusioncontributes to the ultrahigh strength of the as-extruded alloy.

Ultrahigh strength low-cost RE-free Mg-Al-Ca-Mnwrought alloys is also developed in HIT.The as-extruded AXM3404 alloy exhibits superior mechanical strength of TYS = 438 MPa and UTS = 457 MPa, which are mainly attributed to the fine DRXed grains pinned by fine fragmented second phases, and nano-scale dynamic precipitates.Mg-Al-Ca-Mn alloys are promising next generation low-cost ultrahigh-strength alloys without RE elements.

 

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Dr. Mingyi Zheng is currently a professor in the School of Materials Science and Engineering at Harbin Institute of Technology, China. He received his Doctor of Engineering from Harbin Institute of Technology in 1999. He was honored New Century Excellent Talent in University, China in 2008. He has published more than 150 papers in referred journals. Prof. Zheng serves on the Board of Editors of several international journals on materials sciences, such as “Materials Science and Engineering A” and “Journal of Iron and Steel Research, International”. Dr. Zheng's research activities and interests are on the areas of highperformance magnesium alloys, metal matrix composites, and bulk nanomaterials by severe plastic deformation.

 

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