Search

In this study, an AlSi10Cu4Mg alloy was prepared by selective laser melting (SLM) using a mixture of pre-alloyed AlSi10Mg and elemental Cu powders, followed by aging at 180 ℃ for 2 h. The high-temperature tensile properties of both the SLMed and SLM-aged samples were tested in the temperature range of 200–400 ℃, and the microstructure changes during deformation were compared. At the temperature of 200 ℃, the SLMed sample exhibits outstanding tensile properties with an ultimate tensile strength (UTS) of 327±2 MPa and an elongation (EL) of 25.5±0.5 %. This is mainly related to the strain hardening that caused by the accumulation of anomalous dislocations near the high-volume fraction of Si nano-particles within the grains. For the SLM-aged sample, the aging treatment is found to further increase the strength, yielding a UTS of 381±3 MPa. The metastable transition of the Al 2 Cu phase indirectly promotes the precipitation of the nano-sized Si phase during the aging process. As the testing temperature increases, the strength increment of the SLM-aged sample gradually diminishes, while the elongation increment increases. Due to the limited intrinsic thermal stability of Si nano-particles and θ′ phase, the coarsening of the precipitates can weaken the strengthening effect. The dynamic recrystallization process can be accelerated by the aging treatment, thereby helping to improve the elongation. [Display omitted] • The high-temperature tensile properties of AlSi10Cu4Mg alloy prepared by SLM were evaluated. • The SLMed AlSi10Cu4Mg alloy exhibited outstanding comprehensive tensile properties at 200 ℃. • The metastable transition of the Al 2 Cu phase facilitates nano-sized Si precipitation during aging process. • The strength increment of SLM-aged sample gradually diminishes with increasing testing temperature while the elongation increment increases instead. [ABSTRACT FROM AUTHOR]

Modified layers with multiscale structures have been extensively explored and rationally designed on Ti-based orthopedic implants recently, since the remarkable improvement of biomedical properties. In consideration of the inefficiency, costliness and waste products of existing technologies, herein, we proposed the ultrasonic shot peening and induction heating protocol to construct the micro-nano complex oxide structures on Ti6Al4V in term of its advantages of environmental friend, rapid heating, low-cost and easy to process. With the USP pretreatment and induction heating, the nonuniform oxide crystallites firstly appeared on smooth surface and successfully grow up into the well-distributed TiO 2 nanocrystallites, and transformed to netlike structures with submicro-sized worms when subjected to high-power of shot peening, which was significantly influenced by the microstructural evolution of alloy matrix. The submicro/nano-structured oxide layers mainly contained rutile/anatase TiO 2 and little Al 2 O 3 between grain boundaries, successively enhanced the surface roughness and wettability, and tended to form the hydrophilic surfaces. The adhesion strength of the oxide layers to substrates and hardness were also distinctly increased with increasing the IHT period from 20 to 35 s. In vitro BMSCs culturing proved that the prepared submicro/nano-scale oxide layers possessed favorable cell adhesion and proliferation, and further improved the osteogenic differentiation. The novelty of this work was to explored the evolution law of submicro-and nano-scale structures in osteogenic differentiation, and further better clinical application of Ti-based biomaterials. Image 1 • Ultrasonic shot peening and induction heating treatment were jointly proposed. • Microstructure evolution of alloy matrices promoted structure transformation of oxide layers. • Surface roughness, wettability and hardness were markedly improved. • Nano/submicro-structured oxide layers possessed good stem cell compatibility. • Oxide layers with multi-structures further promoted osteogenic differentiation of BMSCs. [ABSTRACT FROM AUTHOR]

It is always challenging to synchronously improve the strength, ductility and corrosion resistances, in the development of magnesium alloys. Herein, a concept called hierarchical precipitate embedded fine grain microstructure is proposed and implemented in an Mg-13Al (wt%) alloy by equal channel angular pressing and aging. Compared to the as-cast alloy, the modified alloy with the designed microstructure has high strength, good ductility, and improved corrosion resistance. The enhancement of mechanical properties is mainly attributed to the synergistic effect of fully recrystallized fine grains (~3.7 µm) and hierarchical β phase (Mg 17 Al 12) precipitates. Although the formation of the hierarchical β phase precipitates in fine-grain Mg matrix can accelerate the initial corrosion in 3.5 wt% NaCl solution due to the galvanic corrosion, the ultimate corrosion resistance is successfully improved by the consumption of exposed Mg anodes and the synergistic barrier effect from the newly-formed corrosion products and corrosion-resistant β phases. ga1 • A concept called hierarchical precipitates embedded fine grain (HP-FG) is proposed. • This strategy provides a way to synchronously enhance multiproperties of Mg alloys. • HP-FG Mg-13Al alloy exhibits enhanced strength, ductility and corrosion resistance. • The unique microstructure confers the excellent multi-properties. • The improved corrosion resistance mainly stems from the hierarchical precipitates. [ABSTRACT FROM AUTHOR]