查看更多>>摘要：Enhancing the bonding strength,optimizing the microstructure and refining the properties represent effective strategies for the fabrication of heterogeneous composite plates.In this study,composite plates of Al/Mg/Al were fabricated through hard plate rolling(HPR)with a reduction in rolling ranging from 40％to 80％.The research primarily concentrates on the substrate in the influence of rolling dynamic recrystallization(DRX)behavior on the grain morphology evolution and mechanical properties of AZ31 magnesium alloy sheets during the process.The findings indicate that at a compression amount of 60％,the composite plate exhibits an ultimate tensile strength(UTS),a maximum elongation(EL)of 12.5％,and improved interface bonding.Comparative analysis reveals the occurrence of DRX on the Mg side,resulting in the formation of small DRXed grains being generated.With an increase in reduction,DRX is facilitated,leading to an initial rise and subsequent decline in the proportion of DRXed grains.The proliferation of fine grains hinder dislocation movement,thereby reinforcing composite plate.Moreover,an elevation in the degree of recrystallization enhances the initiation of non-basal slip and enhances the plasticity of sheet metal.This study offers valuable scientific guidance and technical assistance for the pro-duction of forming high-quality Mg-Al composite plates.
查看更多>>摘要：Understanding the fracture mechanism is essential for optimizing the mechanical properties of titanium alloys.The relationship between fracture behaviour and the multistage lamellar microstructure of the TC18(Ti-5Al-5Mo-5V-1Cr-1Fe)alloy was investigated via in situ tensile and three-point bending tests.The results indicate that the TC1 8 alloy,featuring a multistage lamellar microstructure(including a β matrix,primary lamellar α phase,bundles,and secondary lamellar α phase),exhibits an excellent combination of strength and ductility.The precipitation of the secondary lamellar α phase significantly enhances the alloy's strength but weakens the stress-strain compatibility of the microstructure.This results in a smaller crack-tip plastic zone(CTPZ)and causes dislocations to concentrate more at the grain boundaries and,to a lesser extent,at the phase interfaces.Consequently,in the later stages of crack propagation,microvoids and microcracks tend to form at dislocation pile-ups.With increasing stress,these microvoids and microcracks rapidly coalesce,leading to a greater proportion of intergranular fracture and thus reducing the fracture toughness of the alloy.
查看更多>>摘要：Developing a straightforward strategy for constructing highly processable photonic crystals(PCs)is crucial for various applications,yet remains a challenge.Here,we present a simple polyelectrolyte-induced self-assembly strategy for producing novel photonic crystal(PC)inks with outstanding processing flexibility by adding the polyelectrolytes into the ultralow concentration of colloidal nanoparticle solution.The polyelectrolyte can cover the nanoparticles through the hydrogen bond interaction to induce the aggregation and mutual repulsion of them simultaneously,enabling the self-assembly of ultralow concentration(0.01-1.0 v/v％)of nanoparticles into short-range ordered arrays with angle-independent structural colors.The resulting PC inks present unprecedented pigment-like color modulation capacity,as well as ultrahigh freedom in processing methods due to the fact that the rheological behaviors of PC inks can be widely adjusted by varying the properties of polyelectrolytes.Consequently,the PC inks can be easily shaped into complex and exquisite multicolor patterns/3D structures using various techniques,including injection molding,writing,drawing,and 3D printing.This general approach paves the way for quick and scalable production of advanced PC materials deeply required in practical applications.
查看更多>>摘要：Nanostructuring has shown promise in enhancing the performance of MnO2 for energy storage in supercapacitors,highlighting its technological significance.This study introduces an innovative synthesis method,employing hydrothermal and constant-pressure deposition techniques,to produce nanostructured MnO2/MnS rod electrodes on nickel foam.The roded heterostructure enhances specific surface area,conductivity,and symbiotic effect between MnO2 and MnS.With optimized material and structural advantages,the electrode reaches a capacitance of 977.6 F g-1 at 1 A g-1,demonstrating extended cycling lifespan.Using MnO2/MnS-5h rods as the positive electrode and activated carbon as the negative electrode,the supercapacitor achieves an energy density of 122.23 Wh kg-1 at 898.75 W kg-1.Notably,it maintains 91.55％capacity retention after 5000 cycles at 10 A g-1,indicating outstanding cycling stability.This research presents a promising solution for efficient energy storage,emphasizing the potential application of the developed MnO2/MnS based supercapacitor in high-performance energy storage systems.
查看更多>>摘要：The simultaneous high strength and high plasticity of metastable-β titanium alloy sheets remains a difficult challenge.In this work,a 1.2 mm thick sheet of Ti-15Mo-3Al-2.7Nb-0.25Si titanium alloy was obtained after rolling and annealing,and then subjected to a duplex-ageing treatment.The pre-ageing temperatures fell in the range of 300-390 ℃ for 0.5-2h.The re-ageing temperatures were in the range of 500-600 ℃.After character-ization,it was found that the alloy precipitates ω-phases during the pre-ageing process,and the distribution of such ω-phases evolves unevenly and increases in number with the increase of the pre-ageing temperature.Therefore,the strengthening mechanism of the alloy sheet is mainly α-phase nucleation assisted by ω-phase.Moreover,grain refinement appears as a mechanism to ensure the plasticity of the alloy.Finally the ω-phase evolution law is discussed in detail and the strengthening mechanism of the alloy sheet is also analyzed.At this work,a metastable-β titanium alloy sheet with strength of 1445.75 MPa and elongation of 6.55％was obtained.This study provides a new idea for the microstructure design and process improvement of the metastable-β ti-tanium alloy sheet.
查看更多>>摘要：Refractory high-entropy alloy(RHEA)usually exhibits a high melting point and hence a very high deformation resistance at high temperatures.However,the relatively poor plasticity at room temperature,i.e.,only few RHEAs displaying as-cast tensile ductility,strongly limits the applications of RHEAs as engineering materials.In this work,we show a huge tensile ductility observed in an as-cast TiVNbTa RHEA(～40％fracture elongation)accompanying with a high yield strength(～800 MPa),which are rarely reported properties for RHEAs.The as-cast alloy shows a simple body-centered cubic(BCC)structure with dendrites.Ductile fracture with many dimples is the main fracture mechanism,while no twinning and deformation induced phase transition was observed.The uniform plastic deformation mainly relies on the planar and cross-slip of dislocations.The present result suggests the huge ductility potentials for RHEAs,providing a clue for designs future high performance RHEAs with good ductility.
查看更多>>摘要：The effects of metal/non-metal ratio(M/NM=x:1)on the microstructure and magnetocaloric properties of promising melt-extracted Mn-Fe-P-Si microwires with short heat treatment have been investigated here.More Fe2P principal phase,which is considered favorite for magnetocaloric effect(MCE),should achieve at low M/NM ratio and the fraction of Fe2P phase increased with the reduction of x.Meanwhile,the(Mn,Fe)3Si impurity phase is formed for x=2.00-1.90 whereas change to(Mn,Fe)5Si3 structure for x=1.85.It's worth noting that a metal deficiency resulted in the thermal hysteresis(Thys)and the magnetic hysteresis loss(Wy)decreased by～40％.,The magnetic transition temperature(Ttran),peak value of isothermal magnetic entropy change(-ΔSpeak iso),refrigerant capacity(RC)and effective refrigerant capacity(RCE)first increased then decreased with the decrease of x,and reached the maximums at x=1.90,i.e.,370 K,26.0 J kg-1 K-1,367.4 and 339.8 J kg-1,respectively.Therefore,the customizable microstructure and magnetic properties of the melt-extracted(MnFe)x(P0.5Si0.5)microwires will be achievable effectively by tuning M/NM ratio x,and optimized Mn-Fe-P-Si compounds with novel thermomagnetic properties will be obtained.
查看更多>>摘要：Passive radiation cooling(PRC),as the most promising technology to meet future cooling needs,has attracted great interest.However,there are still huge challenges in manufacturing high-efficiency and low-cost radiant coolers suitable for all-day use.Here,we report a secondary micro-nano shell-hollow structure based on blending method,inspired by the African white beetle Goliathus goliatus.Due to the difference in reflectance between the shell and the internal air,compared with the homogeneous particles,the scattered light has a changed optical path at the interface of the core(air)and the shell(SiO2),and most of the light escapes from the particles,showing strong total internal reflection.The design ingeniously deposits the nano-sized shell-hollow structure on the surface of the micron-sized shell-hollow structure,achieving high solar reflectance(95％)and excellent long-wave infrared emissivity(94％).Sub-ambient cooling of 7.8 and 4.7 ℃ can be achieved at night and daytime,respectively.Silica microspheres with shell and hollow structure can be prepared by soft template method,which is mature,reliable,simple and cheap.Our work provides new ideas for the design and manufacture of high-performance Passive all-day radiative cooling(PARC).
查看更多>>摘要：Porous(Mo2/3Y1/3)2AlC MAX phase ceramic was prepared by reaction sintering method using Mo,Y,Al,and graphite powder as raw materials.The influence of changes in Al content on the purity of the obtained samples was investigated using X-ray diffraction(XRD),scanning electron microscopy(SEM),Archimedes method,and bubble point method.The conditions for obtaining a pure phase were identified,and the transformation path of the phase during sintering and the mechanism of pore formation were provided.The linear sweep voltammetry(LSV)cure and cyclic voltammetry(CV)cure of MAX were tested using an electrochemical workstation.It can be calculated that MAX exhibits good hydrogen evolution reaction(HER)performance under alkaline conditions due to its high electrochemical active surface area(ECSA)of 373.2 and small Tafel slope of 41.7 mV·dec-1.
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