Du Beining

Bio: Du Beining is an academic researcher from Peking University. The author has contributed to research in topics: Alloy & Microstructure. The author has an hindex of 4, co-authored 11 publications receiving 65 citations.

Influence of Tantalum Addition on Microstructure and Mechanical Properties of the Nial-Based Eutectic Alloy

Abstract: NiAl-28Cr-6Mo or NiAl-Cr(Mo) eutectic alloys with different degree of tantalum (Ta) addition have been fabricated and investigated. The microstructural characterization shows that minor Ta addition results in the formation of Cr2Ta Laves phase with C14 crystal structure. Small Laves phases are prone to precipitation along Cr(Mo) phase boundary, while large/bulk ones are formed in the intercellular region. As compared with the NiAl-Cr(Mo) eutectic alloy, minor Ta addition can refine Cr(Mo) and NiAl eutectic lamella in the core of eutectic cell but coarsen the Cr(Mo) and NiAl phase in the fringe of eutectic cell. An increased Ta addition invokes coarsening of Cr(Mo) and NiAl phases in the intercellular region and enhances Laves phase precipitation in the intercellular region. When the Ta addition increases to 2.0 at.%, the modified alloy mainly comprises ultrafine eutectic cell core and coarse Cr(Mo) and NiAl phases, which are semi-separated by NiAl dendritic and bulk Laves phase. The results confirm that the appropriate Ta addition can significantly improve the high-temperature strength with a feeble effect on room-temperature ductility, which can be ascribed to the microstructure optimization induced by the Ta addition. However, further Ta addition strongly affects the cellular eutectic microstructure and is detrimental for the roomtemperature ductility. The appropriate Ta content in the NiAl-Cr(Mo) eutectic alloy should be about 1.0 at.%.

Multifunctional, Robust, and Porous PHBV-GO/MXene Composite Membranes with Good Hydrophilicity, Antibacterial Activity, and Platelet Adsorption Performance.

Abstract: The limitations of hydrophilicity, strength, antibacterial activity adsorption performance of the biobased and biocompatible polymer materials, such as polyhydroxyalkanoates (PHAs), significantly restrict their wider applications especially in medical areas. In this paper, a novel composite membrane with high antibacterial activity and platelet adsorption performance was prepared based on graphene oxide (GO), MXene and 3-hydroxybutyrate-co-hydroxyvalerate (PHBV), which are medium-chain-length-copolymers of PHA. The GO/MXene nanosheets can uniformly inset on the surface of PHBV fibre and give the PHBV—GO/MXene composite membranes superior hydrophilicity due to the presence of hydroxyl groups and terminal oxygen on the surface of nanosheets, which further provides the functional site for the free radical polymerization of ester bonds between GO/MXene and PHBV. As a result, the tensile strength, platelet adsorption, and blood coagulation time of the PHBV—GO/MXene composite membranes were remarkably increased compared with those of the pure PHBV membranes. The antibacterial rate of the PHBV—GO/MXene composite membranes against gram-positive and gram-negative bacteria can reach 97% due to the antibacterial nature of MXene. The improved strength, hydrophilicity, antibacterial activity and platelet adsorption performance suggest that PHBV—GO/MXene composite membranes might be ideal candidates for multifunctional materials for haemostatic applications.

Hot Extrusion Effect on the Microstructure and Mechanical Properties of a Mg–Y–Nd–Zr Alloy

Abstract: Mg–Zn–Y–Nd alloy was prepared by casting and hot extrusion. The microstructure and mechanical properties of OM, SEM, XRD, TEM, and tensile tests were investigated with casting and hot extruded alloys. The results demonstrate that in a casting Mg–Y–Nd–Zr alloy, the α-Mg matrix is separated into the cell structure by a discontinuously distributed coarse Mg24Y5/α-Mg eutectic structure and fine Mg12Nd particles. TEM analysis shows that the Mg12Nd and Mg24Y5 phases have the orientation of $$ {\left[001\right]}_{{\mathrm{Mg}}_{12}\mathrm{Nd}}//{\left[0221\right]}_{\upalpha -\mathrm{Mg}} $$ , and $$ {\left[111\right]}_{{\mathrm{Mg}}_{24}{\mathrm{Y}}_5}//{\left[0001\right]}_{\upalpha -\mathrm{Mg}} $$ and $$ {\left(10\overline{1}\right)}_{{\mathrm{Mg}}_{24}{\mathrm{Y}}_5}//{\left(10\overline{1}0\right)}_{\upalpha -\mathrm{Mg}} $$ , respectively. The hot extrusion separates the Mg24Y5/α-Mg eutectic structure into fragments and aligns fragmentary Mg24Y5 particles along the extrusion direction. The interaction of hot extrusion and strengthening particles refines the α-Mg matrix greatly. Moreover, large strains result in the stacking faults of the matrix. As compared to the casting alloy, the hot-extruded one exhibits high yield strength, ultimate tensile strength, and elongation, which should be ascribed to the grain fineness, optimum distribution of strengthening particles and multiple substructures.