Browsing by Author "Zhang, DL"

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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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    In situ synchrotron high-energy x-ray diffraction analysis on phase transformations in Ti-Al alloys processed by equal-channel angular pressing
    (Wiley-Blackwell, 2009-11) Liss, KD; Whitfield, RE; Xu, W; Buslaps, T; Yeoh, LA; Wu, XL; Zhang, DL; Xia, KN
    Mixtures of 47-Al and 53-Ti powders (atomic %) have been consolidated using back pressure equal-channel angular pressing starting with both raw and ball-milled powders. In situ synchrotron high-energy X-ray diffraction studies are presented with continuous Rietveld analysis obtained upon a heating ramp from 300 K to 1075 K performed after the consolidation process. Initial phase distributions contain all intermetallic compounds of this system except Al, with distribution maxima in the outer regions of the concentrations (α-Ti, TiAl3). Upon annealing, the phase evolution and lattice parameter changes owing to chemical segregation, which is in favour for the more equilibrated phases such as γ-TiAl, α(2)-Ti3Al and TiAl2, were followed unprecedentedly in detail. An initial δ-TiH2 content with a phase transition at about 625 K upon heating created an intermediate β-Ti phase which played an important role in the reaction chain and gradually transformed into the final products. © 2009, Wiley-Blackwell.
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    Towards the thermodynamic equilibrium of titanium aluminides after consolidation by back pressure equal channel angular pressing
    (ARC Centre of Excellence for Design in Light, 2007-12) Xu, W; Wu, X; Whitfield, R; Liss, KD; Buslaps, T; Yeoh, LA; Zhang, DL; Xia, K