Browsing by Author "Geng, HW"

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    Annealing-induced strengthening and stabilization in ultrafine-grained Al and Al–Mg alloys prepared by rapid powder consolidation
    (Elsevier, 2022-01-26) Zhou, DS; Bu, YF; Muránsky, O; Geng, HW; Sun, BH; Yang, C; Zhang, DL
    Annealing usually softens Al–Mg based alloys due to grain coarsening. This work shows that annealing induces strengthening in bulk ultrafine-grained Al and Al-(2.5, 5 and 7.5) at.% Mg samples fabricated by mechanical alloying and rapid powder extrusion. Experimental investigation of the microstructure of the annealed samples reveals that the annealing promotes in-situ formation of nanoscale dispersoids which strongly suppresses grain growth and recrystallization. The in-situ formed nanodispersoids warrant high thermal stability of the ultrafine-grained matrix microstructure and improve the strength of the as-extruded samples while maintaining their good ductility. The present findings offer an exciting pathway in developing thermally stable ultrafine-grained Al–Mg based alloys with a notable combination of high strength and good ductility. © 2021 Elsevier B.V
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    Multiple strengthening mechanisms in high strength ultrafine-grained Al–Mg alloys
    (Elsevier, 2020-01-13) Wang, H; Geng, HW; Zhou, DS; Niitsu, K; Muránsky, O; Zhang, DL
    High strength has always been pursued in binary Al–Mg and 5xxx series Al alloys. However, these alloys usually provide medium strength due to lack of multiple strengthening methods. Here, this study reports on multiple strengthening effects existing in a binary ultrafine-grained (UFG) Al-7.5at.%Mg alloy prepared by mechanical alloying and hot extrusion. Different strengthening mechanisms, in particular, dispersoid strengthening and stacking fault strengthening, are analyzed and evaluated in terms of their respective contribution to the 511 MPa yield strength of the alloy. The strengthening analysis proves that the concurrent generation of nanoscale dispersoids and stacking faults (SFs) can be used as a new microstructural design in developing novel Al–Mg-based alloys with higher strength and enhanced ductility. © 2019 Elsevier B.V.