Zinc (Zn) alloys have attracted much attention for biomedical applications due to their biodegradability, biocompatibility, and biological functionalities. Zn alloy foams have high potential to be ...used as regenerative medical implants by virtue of their porous structure, which allows new bone tissue ingrowth, their low elastic modulus approximating that of natural bone, and their biodegradation, which eliminates the need for follow-up surgery to remove the implants after bone tissue healing. In this context, a biodegradable Zn–Cu foam was fabricated by electrochemical deposition on a foamed Cu template and given a subsequent diffusion heat treatment. The microstructure, mechanical properties, degradation behavior, toxicity, hemolysis percentages, and antibacterial effects of the Zn–Cu foams were assessed for biomedical applications. The Zn–Cu foams exhibited a yield strength of ~12.1 MPa, a plateau strength of 16.8 MPa, and a strain over 50% under compression tests. The corrosion rate of the Zn–Cu foams measured by electrochemical polarization testing was 0.18 mm/y. The Zn–Cu foams showed good blood compatibility with a hemolysis percentage of less than 5%. Cytotoxicity assessment indicated that a 100% concentration of the Zn–Cu foam extract showed clear cytotoxicity against MC3T3-E1 osteoblast cells, but a 12.5% concentration of the extract showed > 90% cell viability. Moreover, the Zn–Cu foams showed good antibacterial effects.
This work reportsa biodegradable Zn–Cu foam with high mechanical strength and ductility, suitable degradation rate, good antibacterial capacity, and good hemolysis property and biocompatibility. The Zn–Cu foam exhibited a yield strength of ~12.1 MPa, a plateau strength of 16.8 MPa, and a strain over 50% under compression tests. The corrosion rate of the Zn–Cu foam measured by electrochemical polarization testing was 0.18 mm/y in Hanks’ Solutions. The Zn–Cu foam showed good blood compatibility with a hemolysis percentage of less than 5%. Cytotoxicity assessment indicated that a 12.5% concentration of the foam extract showed > 90% cell viability. Moreover, the Zn–Cu foam showed good antibacterial effects against S. aureus.
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This study focuses on the uniaxial compressive behaviour of thin-walled Al alloy tubes filled with pyramidal lattice material. The mechanical properties of an empty tube, Al pyramidal lattice ...material, and pyramidal lattice material-filled tube were investigated. The results show that the pyramidal lattice material-filled tubes are stronger and provide greater energy absorption on account of the interaction between the pyramidal lattice material and the surrounding tube.
Metallic three-dimensional lattice structures exhibit many favorable mechanical properties including high specific strength, high mechanical efficiency and superior energy absorption capability, ...being prospective in a variety of engineering fields such as light aerospace and transportation structures as well as impact protection apparatus. In order to further compare the mechanical properties and better understand the energy absorption characteristics of metal lattice structures, enhanced pyramidal lattice structures of three strut materials was prepared by 3D printing combined with investment casting and direct metal additive manufacturing. The compressive behavior and energy absorption property are theoretically analyzed by finite element simulation and verified by experiments. It is shown that the manufacturing method of 3D printing combined with investment casting eliminates stress fluctuations in plateau stages. The relatively ideal structure is given by examination of stress–strain behavior of lattice structures with varied parameters. Moreover, the theoretical equation of compressive strength is established that can predicts equivalent modulus and absorbed energy of lattice structures.
Auxetic materials are a class of materials that expand transversely when stretched longitudinally. Recently, auxetic materials are gaining special interest in wide range of applications mainly due to ...their attractive mechanical behavior. In this study, we focus on the compressive properties of new three-component auxetic composite-filled tubes including empty tubes, auxetic lattice structures and polymer fillers. The compressive behavior of three-component auxetic composite-filled tubes, auxetic composites and empty tube was investigated by means of finite element analysis (FEA) and experimental method. The results indicated that the auxetic composite-filled tubes exhibit superior behavior compared with both the empty tube and auxetic composites, even significantly higher stress than the sum of total thereof. This feature is related to the interaction effect and additional support between the three components. The energy absorption characteristics and deformation modes of the auxetic composite-filled tubes and empty tube were also ascertained. It was concluded that inserting auxetic composite as a filler material inside the empty tube significantly improved its energy absorption, as well as delaying crack initiation and propagation in the empty tube.
In this paper, we investigate the effects of vanadium on the strength and ductility of medium-manganese steels by analyzing the microstructural evolution and strain hardening rates and performing ...quantitative calculations. Two significantly different contents of vanadium, 0.05 and 0.5 wt.%, were independently added to model steel (0.12C-10Mn) and annealed at different intercritical temperatures. The results show that higher vanadium addition increases the yield strength but decreases the ductility. The maximum yield strength can increase from 849 MPa to 1063 MPa at low temperatures. The model calculations reveal that this is due to a precipitation strengthening increment of up to 148 MPa and a dislocation strengthening increment of 50 MPa caused by a higher quantity of V
C
precipitates. However, the high density of vanadium carbides leads them to easily segregate at grain boundaries or phase interfaces, which prevents strain from uniformly distributing throughout the phases. This results in stress concentrations which cause a high strain hardening rate in the early stages of loading and a delayed transformation-induced plasticity (TRIP) effect. Additionally, the precipitates decrease the austenite proportion and its carbon concentrations, rendering the TRIP effect unsustainable. Accordingly, the ductility of high vanadium steels is relatively low.
The vanadate conversion coating (VCC) was formed on the surface of magnesium (Mg) alloy in vanadium phosphate solution, as well as the cathode electrophoresis and bake-curing treatments of the ...conversion coating proceeded. According to the addition of vanadate in the solution, the conversion coating is refined crystalline and possesses low weight loss during electrophoresis and bake-curing treatment processes. Besides, when the content of NaVO3 is 4g/L in vanadate solution, not only the microstructure of conversion coating is the most refined, but also the adhesion and corrosion resistance of electrophoretic paint coating (EPC) is the best. On the other hand, the “rare earth phosphating VS low-temperature electrophoresis” technique is suitable for Mg alloy coatings. As seen in scanning electron microscope (SEM), the VCC reveals three-dimensional net structure, which provides a well underlayer for the adhesion between electrophoretic paint and the samples.
This study investigates the structure and corrosion behavior of the Al0.8CrFeCoNiCu0.5 high-entropy alloy prepared using non-consumable vacuum arc melting. XRD analysis identified BCC1 and BCC2 ...phases corresponding to (Fe-Cr) and Al-Ni, respectively, while the FCC phase aligned with Cu. SEM and EBSD observations confirmed an equiaxed grain structure with fishbone-like morphology at grain boundaries and modulated structures within the grains. The alloy exhibited minimal residual stress and strain. The alloy demonstrated a preferred orientation of grain growth along the direction. Electrochemical testing in a 3.5% NaCl solution revealed a corrosion potential of −0.332 V and a corrosion current density of 2.61 × 10−6 A/cm2. The intergranular corrosion regions exhibited significant depletion of Al and Cu elements, with the corrosion products primarily consisting of Al and Cu. Al and Cu elements are susceptible to corrosion. The wear scar width of Al0.8CrFeCoNiCu0.5 high-entropy alloy is 1.65 mm, which is less than 45# steel, and high-entropy alloy has more excellent wear resistance. Given its unique attributes, this high-entropy alloy could find potential applications in high-end manufacturing industries such as the aerospace engineering, the defense industry, energy production, and chemical processing where high corrosion resistance and wear resilience are crucial.
As one of the lightest structural metals, the application breadth of aluminum alloys is, to some extent, constrained by their relatively low wear resistance and hardness. However, laser cladding ...technology, with its low dilution rate, compact structure, excellent coating-to-substrate bonding, and environmental advantages, can significantly enhance the surface hardness and wear resistance of aluminum alloys, thus proving to be an effective surface modification strategy. This review focuses on the topic of surface laser cladding materials for aluminum alloys, detailing the application background, process, microstructure, hardness, wear resistance, and corrosion resistance of six types of coatings, namely Al-based, Ni-based, Fe-based, ceramic-based, amorphous glass, and high-entropy alloys. Each coating type’s characteristics are summarized, providing theoretical references for designing and selecting laser cladding coatings for aluminum alloy surfaces. Furthermore, a prediction and outlook for the future development of laser cladding on the surface of aluminum alloys is also presented.
A Fe–Al intermetallic layer was formed on the surface of T91 heat-resistant steel by a molten aluminum hot-dipping and heat diffusion treatment. It is shown that the layer was composed of Al, FeAl3 ...and Fe2Al5 phases in the as-dipped state while only Fe3Al phase retained after the heat treatment. The intermetallic layer exhibited typical columnar grain structure after the heat treatment, and the thickness of aluminizing layer was increased from 55μm at 760°C to around 100μm at 1050°C heat treatment. Such a phase composition and grain morphology are favorable for the oxidation and corrosion resistance of T91 steel.
Due to its low melting point and high hardness, Ni60 (Ni-Cr-B-Si) alloy is widely used as surface cladding material for mould steel. In present study, Ni60 alloy thin-walled samples were fabricated ...using laser metal deposition (LMD) technology on H13 steel substrate which is usually used as mould material. The microstructure and mechanical properties (microhardness and wear resistance) of LMD Ni60 alloy were investigated. The results show that the LMD Ni60 alloy sample is mainly composed of Ni, Ni3Fe, Ni3B, Ni3Si, CrB, Cr5B3 and Cr7C3. The microstructures of the sample mainly include Ni-B-Si eutectics, Ni columnar dendrites and precipitates (boride and carbide). In the region with faster cooling rate of the sample, eutectics take a larger proportion, meanwhile precipitates are refined and dispersed uniformly. So hardness of the region can reach 950 HV. In the interlayer region, eutectics decrease while Ni dendrites increase because of the influence of remelting. The hardness of this region is about 750 HV. Wear resistance tests indicated that the wear resistance of LMD Ni60 alloy is about 9 times of H13 steel.
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