In this study, effects of initial orientation on microstructure evolution and mechanical properties of AZ31 Mg alloy sheets via accumulated extrusion bonding(AEB) was systematically studied. The samples with RD and TD...
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In this study, effects of initial orientation on microstructure evolution and mechanical properties of AZ31 Mg alloy sheets via accumulated extrusion bonding(AEB) was systematically studied. The samples with RD and TD parallel to extrusion direction(ED) were labeled as RED and TED, respectively. RD and TD pieces alternately stacked was named as RTED. The results revealed that under three-dimensional compressive stress, {10-12} tensile twinning dominated the first stage deformation in container. As the plunger continuous press down, dynamic recrystallization(DRX) occurred, and the newly fine DRXed grains along original and twin grain boundaries gradually consumed the matrix and twin grains. The microstructure was completely transformed into recrystallized grain structure at sizing band with an average grain size of ～0.9 μm in TED sample, smaller than that of RED *** the alloys extruded out of the die, DRXed grains significantly grew to ～4.5 μm and 3.5 μm for RED and TED samples, respectively. A laminated microstructure was obtained with average grain sizes of～4.4 μm in RD layers and 3.5 μm in TD layers for RTED sample. The AEB processed samples exhibited an ED-tilt double-peak basal texture with similar texture intensity. The tensile tests results indicated that attributed to the combined effect of grain refinement and texture evolution, the yield strength and fracture elongation of RED and TED samples was significantly improved. The heterogeneous microstructure in RTED sample induced an extra work hardening(HDI-work hardening) in tensile deformation and resulted in a further improved elongation of 32.0%.
Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase mul-tielement Ni42-xCu8CoxMn37Ga13(8 ≤ x ≤ 12)alloys by performing thermomechanical ***,anomalous dependence of the marte...
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Significant two-way shape memory effect(TWSME)was achieved in single crystals of single-phase mul-tielement Ni42-xCu8CoxMn37Ga13(8 ≤ x ≤ 12)alloys by performing thermomechanical ***,anomalous dependence of the martensitic transformation temperature span on Co content was *** training,quite a narrow temperature span of the martensitic transformation,nearly independent of the Co content,was observed in all single *** training the temperature span was still narrow for 8 ≤ x ≤ 10.9 but was obviously expanded for 10.9＜x ≤ ***-resolution transmission electron microscopy revealed that at the atomic scale,there exists incommensurate modulated structure in the single phase single crystals,as evidenced by nonperiodic satellite spots in the selected area electronic diffraction ***,the modulated wave vector of the satellite spots was increased by higher Co *** first principal calculations it was considered that the incommensurate modulated structure originates from the formation of Co-Co *** training arrays of ordered dislocations with the same Burgers vector were introduced for 8 ≤ x ≤ 10.9 but the network of dislocations was formed for 10.9＜x ≤ *** on analysis of transmission electron microscopy,geometric phase,thermody-namics,and Landau theory,it was considered that the austenite/martensite phase interface was pinned by the network of dislocations,expanding the temperature span of the martensitic *** work supplies new insights for understanding the microstructure and martensitic transformation of Ni-Mn-Ga-based alloys.
Nowadays,the predominant source for approximately 90%of epoxy resin materials worldwide is the diglycidyl ether of bisphenol A(DGEBA).However,the increasing recognition of environmental concerns,such as global warming...
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Nowadays,the predominant source for approximately 90%of epoxy resin materials worldwide is the diglycidyl ether of bisphenol A(DGEBA).However,the increasing recognition of environmental concerns,such as global warming and the depletion of petroleum reserves,necessitates the exploration of alternative options,specifically bio-epoxy resin derived from sustainable ***,the inadequate flame retardancy of bio-epoxy resin presents a notable drawback,limiting its applicability in high-risk *** objective of this review article is to provide a concise overview of the latest and upto-date advances in flame-retardant epoxy resins derived from sustainable ***,the discussion encompasses inherently flame-retardant bio-based epoxy resins,considering both bio-based epoxy monomers and bio-based curing agents,focusing on their flame retardancy and mechanical ***,the utilization of phosphorus-containing and silicon-containing additives in bio-based epoxy is ***,a comprehensive evaluation of partially bio-based intrinsically flame retardant epoxy resins is ***,this article offers an extensive survey of the current state-of-the-art in the field and presents future perspectives,serving as a valuable resource for researchers engaged in the study of flame-retardant epoxy resins derived from sustainable resources.
The extruded Mg–4Zn–1Mn alloy was prepared and its in vitro corrosion behavior in different physiological solutions of simulated body fluid（SBF）, artificial saliva（AS） and artificial urine（AU） was investigated...
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The extruded Mg–4Zn–1Mn alloy was prepared and its in vitro corrosion behavior in different physiological solutions of simulated body fluid（SBF）, artificial saliva（AS） and artificial urine（AU） was investigated for biomedical applications. The microstructural characterization by optical microscope（OM）, X-ray diffractometer（XRD）, scanning electron microscopy（SEM） and energy dispersive X-ray spectrometer（EDS） showed that the alloy with an average grain size of approximate 20 μm was mainly composed of α-Mg matrix phase along with some MgZn2and α-Mn precipitates. The results of electrochemical corrosion and immersion corrosion tests revealed a distinct corrosion behavior for the alloy in different solutions with increasing immersion time. The corrosion morphologies were featured with flocculent precipitates in the SBF, flower-like clusters in the AS and columnar crystals in the AU. The alloy exhibited highest corrosion resistance and lowest corrosion rate in the AS compared with the SBF and the AU, which was attributed to the formation of a stable corrosion products layer.
Heterogeneous pressure-carrying medium was employed to establish a differentiated pressure field on sheet metal in flexible die forming process in this work,which aimed at matching the non-symmetric shape of target co...
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Heterogeneous pressure-carrying medium was employed to establish a differentiated pressure field on sheet metal in flexible die forming process in this work,which aimed at matching the non-symmetric shape of target component and improving metal inflow to avoid local tensile ***,metal inflow corresponding to the differentiated pressure field was analytically *** of a typical non-symmetric shell component was experimentally and numerically studied based on the proposed *** with forming processes based on the uniform pressure,difference of metal inflow in two sides of the non-symmetric component increased from 2.16 mm to 3.36 mm and metal inflow in critical region increased by 11.9%when differentiated pressure field(taking heterogeneous elastomer#4–3 for example)was *** resultant maximum thinning ratio decreased by 4.2% and the uniformity of shell thickness increased by 16.9%.With the decrease of Shore hardness of elastomer in the formed region,stress path in the ready-to-form region transferred towards the bi-axial tension stress state,i.e.,stress ratio(a)***,stress triaxiality(η)in characteristic regions were regulated appropriately,which decreased the risk of tensile *** was attributed to the decreased normal pressure and frictional resistance at sheet/elastomer interface in the formed region.
In this paper,the metastableβTB8 titanium alloy with nanocrystallineαphase is achieved by electric pulse *** morphology evolution and variant selection of nanocrystallineαphase in metastableβTB8titanium alloy were...
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In this paper,the metastableβTB8 titanium alloy with nanocrystallineαphase is achieved by electric pulse *** morphology evolution and variant selection of nanocrystallineαphase in metastableβTB8titanium alloy were investigated by using scanning electron microscope(SEM),electron backscattered diffraction(EBSD)and transmission electron microscope(TEM)*** results indicated that the morphologies of the nanocrystallineαphase were mainly triangular clusters and needle-like at the pressure of 0 *** increasing pressure from 20 to 50 MPa,the volume fraction of needlelikeαphase decreased,and a large amount of V-shapedαphase formed in the interior ofβ*** on the EBSD data,the parentβphase was reconstructed by MTEX *** the interior of theβgrains,12 variants can form for the samples electric pulse treated at 0 and20 MPa,while only 3 and 6 variants can form for the samples electric pulse treated at 30 and 50 *** the grain boundary of theβgrains,one or more grain boundaryαvariants can be generated for the samples electric pulse treated at different pressures as long as one of the neighborβgrains follows the Burgers orientation relationship.
Superior to ferromagnetic (FM) valleytronics, antiferromagnetic (AFM) counterparts exhibit ultradense and ultrafast potential due to their intrinsic advantages of zero stray field, terahertz dynamics, and compensated ...
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Superior to ferromagnetic (FM) valleytronics, antiferromagnetic (AFM) counterparts exhibit ultradense and ultrafast potential due to their intrinsic advantages of zero stray field, terahertz dynamics, and compensated moments of antiferromagnets. However, the physics of spontaneous valley polarization is mainly rooted in FM hexagonal lattices and is rarely used to explore the simultaneous spin and valley polarizations in AFM materials. Here, we propose a general stacking method to achieve valley polarization in AFM bilayer systems. The hexagonal ferrovalley material is used as the basic building unit, and then the space-inversion centrosymmetric bilayer system with interlayer AFM ordering is constructed by horizontal mirror and twofold rotational operations, which can exhibit spontaneous valley polarization. In this construction process, the rarely explored layer-locked hidden valley polarization, hidden Berry curvature, and layer Hall effect are involved, and an out-of-plane electric field can be used to detect hidden valley polarization and to realize layer-locked anomalous valley Hall effect. We use three examples to illustrate our proposal. First, the Janus GdBrI is used to illustrate concepts and effects involved in our design process. Second, the RuBr2 is used to demonstrate other phenomena, including valley polarization transition and near-ideal quantum spin Hall insulators. Finally, we use our design principles to understand the valley polarization of experimentally synthesized MnSe from a new perspective. Our works establish a robust general scheme to achieve valley polarization in AFM bilayer systems, thereby opening up new avenues for AFM valleytronics.
This research is an analysis of a unique high-density honeycomb foam named Lantor Soric, a flexible core material specifically used for resin infusion. To understand the full scope of this unique core material, it was...
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A new ultra-fine tungsten carbide(WC)cemented carbide was fabricated by spark plasma sintering(SPS),in which the CoCrNiCuFe high entropy alloy(HEA)was used as the binder and was mixed with WC carbide through the mecha...
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A new ultra-fine tungsten carbide(WC)cemented carbide was fabricated by spark plasma sintering(SPS),in which the CoCrNiCuFe high entropy alloy(HEA)was used as the binder and was mixed with WC carbide through the mechanical ball milling *** microstructure of WC-10 wt%HEA compos-ites was investigated through scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD),and differential scanning calorimetry-thermogravimetric analysis(DSC-TG).The results show that the interface characteristics of the WC/HEA system include the FCC(111)//HCP(101^(-)1)interface with stable ionic bonds and the interface that reacts due to the formation of the(Fe,Co)_(3)W_(3)C *** mechanical properties of WC-10 wt%HEA composites were investigated through the Vickers hardness test,friction and wear tests,and compression *** WC-10 wt%HEA composites exhibit good fracture toughness and hardness of 10.98 MPa m^(1/2)and 1988.60 HV30,*** compressive strength at room temperature and 800℃is up to 3307 and 1747 MPa,*** composites exhibited excellent properties attributed to the good wettability of HEA on WC grains and the consequent strengthening effect on the WC/WC interfaces.
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