Spark plasma sintered Mg-4Y-3Nd with exceptional tensile performance


This work utilizes the spark plasma sintering (SPS) technique and exploits the physical mechanisms leading to the preparation of a fully compacted Mg-4wt.%Y-3wt.%Nd (WN43) material to exhibit superb mechanical properties, including outstanding plastic elongation in tension of more than 10 % among the SPS-ed Mg-based materials. To this end, the detrimental effect of oxide shells present on the Mg-Y-Nd powder particles is purposefully suppressed. The essential principle underlying the strong interconnection of the former powder particles is based on the combination of sufficiently high pressure and temperature approaching the eutectic points of Mg-Y/Nd systems. Thus-prepared WN43 material also retains the initial fine powder microstructure and its microstructural features are translated into good ductility and strength of the final product comparable with the conventionally-prepared (e.g. wrought) Mg-RE alloys. At the same time, the advantages of SPS – the production of a relatively large volume of near net-shape material with weak crystallographic texture – are retained. The deformation mechanisms are investigated by means of complementary in-situ techniques (acoustic emission, digital image correlations) and semi in-situ electron backscatter diffraction. A relatively low tension–compression asymmetry is revealed owing to the weak texture and the activity of deformation mechanisms (dislocation slip and twinning) follows the conventions of bulk Mg. In support of potential practical applications of the material, no significant cracking of the residual oxide phases is observed although they seem to play some role in the initiation of critical crack leading to the fracture. The SPS technique offers undemanding fine-tuning of processing parameters leading, in turn, to expeditious modification of material properties and, given the understanding of microstructure evolution unveiled in this work, it can be effectively utilized for the preparation of different Mg-based (or other) materials.
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