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Tensile and cyclic deformation response of friction-stir-welded dissimilar aluminum alloy joints:Strain localization effect

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Journal of Materials Science & Technology 2021年第14期73卷 91-100页

作者： P.l.Niu W.Y.li d.l.chen State Key laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi'an710072.China department of Mechanical and Industrial Engineering Ryerson University350 Victoria StreetTorontoOntarioM5B2K3Canada

Cyclic deformation behavior of friction-stir-welded dissimilar AA2024-T351 to AA7075-T65 aluminum alloy joints was evaluated via stepwise tests at different strain rates,along with transmission electron microscopy examinations to characterize the precipitates required to assess internal *** backscatter diffraction was employed to observe the inhomogeneous microstructures of the FSWed *** localization appeared in the heat affected zone(HAZ)of AA2024 *** cyclic deformation of 500 cycles at a total strain amplitude of 0.5%,the strength of the dissimilar joints resumed basically to that of AA2024 base *** the AA2024 HAZ was obviously hardened,which should be attributed to the introduced dislocations during cyclic deformation *** hardening capacity of the joints increased with decreasing strain rate.

关键词： Friction stir welding dissimilar aluminum alloys Strain localization Cyclic hardening Slip irreversibility

de-twinning and Texture Change in an Extruded AM30 Magnesium Alloy during Compression along Normal direction

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Journal of Materials Science & Technology 2015年第3期31卷 264-268页

作者： d.Sarker J.Friedman d.l.chen department of Mechanical and Industrial Engineering Ryerson University

Twinning and de-twinning are the salient deformation mechanisms in hexagonal close-packed(hcp)metals. The aim of this study was to examine and quantify the de-twinning process involving a reversible motion of twin boundaries in an extruded AM30 magnesium alloy after re-compression along the normal direction(Nd) of pre-compressed samples along the extrusion direction(Ed). {1012} extension twins were first introduced at a compressive strain of 3.7% along the Ed. The subsequent compressive deformation along the Nd induced a gradual shrinkage of twins with increasing cumulative true strain,and the complete de-twinning occurred at a strain of ~7.7%. The twin width decreased linearly with increasing true strain. Texture measurements verified the rotation of c-axes of hcp unit cells towards the anti-compression direction due to {1012} extension twinning after compression along the Ed, and a gradual return of c-axes to the initial orientation due to twin shrinking or de-twinning during the following compression along the Nd. The {1012} twinning corresponded to the formation of new texture components C{1210} and d{0110} and a decrease in the initial texture components A{0001} and B{0001}, while the twin shrinking or de-twinning was characterized by a gradual vanishing of components C{1210} and d{0110} and an increase in the components A{0001} and B{0001}.

关键词： Magnesium alloy Compressive deformation Twinning d

Achieving superior strength-ductility synergy in a heterostructured magnesium alloy via low-temperature extrusion and low-temperature annealing

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Journal of Materials Science & Technology 2023年第32期163卷 32-44页

作者： H.Wang d.T.Zhang C.Qiu W.W.Zhang d.l.chen Guangdong Key laboratory for Advanced Metallic Materials Processing and Forming National Engineering Research Center of Near-net-shape Forming for Metallic MaterialsSouth China University of TechnologyGuangzhou 510640China department of Mechanical and Industrial Engineering Toronto Metropolitan University(formerly Ryerson University)350 Victoria StreetTorontoON M5B 2K3Canada

A low-alloyed Mg-1.2Zn-0.1Ca(wt.%)alloy was fabricated via low-temperature extrusion and annealing at 250℃for different times(10,30,and 90 min)to attain heterostructures with different fine-grained fractions,focusing on the effect of heterostructure on the mechanical *** dynamic recrystallization(RX)occurred during extrusion at 150℃,and a lamellar structure consisting of fine RX grains and coarse unRX grains was *** subsequent annealing promoted static RX in the as-extruded alloy,leading to an increased fine-grained fraction from 67%to 95%.Meanwhile,the co-segregation of Zn and Ca atoms impeded the migration of grain boundaries,thus achieving a fine grain size of 0.8–1.6μ*** sample annealed for 10 min with a fine-grained fraction of 73%and an average RX grain size of 0.9μm exhibited a superior combination of high yield strength(305 MPa)and good ductility(20%).In comparison,an excellent elongation of 30%was achieved in the alloy with a nearly fully-RXed microstructure and an average grain size of 1.6μm after 90 min annealing,despite a lower yield strength of 228 *** unRX grains,the hard orientation with(01–10)parallel to the extrusion direction and high-density dislocations made it more difficult to deform compared with the RX grains,thus producing hetero-deformation induced(HdI)*** fine grains and high-density dislocations,HdI strengthening is the key to achieving the superior mechanical properties of the low-alloyed Mg alloy.

关键词： low-alloyed magnesium alloy low-temperature extrusion Annealing Heterostructure Mechanical properties

Microstructure and Strain Hardening of a Friction Stir Welded High-Strength Al–Zn–Mg Alloy

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Acta Metallurgica Sinica(English letters) 2014年第4期27卷 723-729页

作者： A.H.Feng d.l.chen Z.Y.Ma W.Y.Ma R.J.Song School of Materials Science and Engineering Tongji University State Key laboratory of Advanced Welding Production Technology School of Materials Science and EngineeringHarbin Institute of Technology department of Mechanical and Industrial Engineering Ryerson UniversityTorontoON M5B 2K3Canada Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

Microstructural evolution and strain hardening behavior of a friction stir welded（FSWed） high-strength7075Al-T651 alloy were *** nugget zone was observed to consist of fine and equiaxed recrystallized grains with a low dislocation density and free of original precipitates,but containing uniformly distributed *** strength,joint efficiency,and ductility of the FSWed joints increased with increasing welding speed.A joint efficiency of ＊91% was achieved at a welding speed of 400 mm/min and rotational rate of 800 r/min,while the ductility remained basically the same as that of the base *** was no obvious strain rate sensitivity observed in both base metal and welded *** both the base metal and FSWed joints exhibited stage III and IV hardening characteristics,the hardening capacity,strain hardening exponent,and strain hardening rate all increased after friction stir welding.

关键词： Aluminum alloy Friction stir welding Mechanical properties Strain hardening

Hot deformation and Work Hardening Behavior of an Extruded Mg–Zn–Mn–Y Alloy

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Journal of Materials Science & Technology 2015年第12期31卷 1161-1170页

作者： N.Tahreen d.F.Zhang F.S.Pan X.Q.Jiang d.Y.li d.l.chen department of Mechanical and Industrial Engineering Ryerson University College of Materials Science and Engineering Chongqing University National Engineering Research Center for Magnesium Alloys Chongqing University Advanced Materials Research Center Chongqing Academy of Science and Technology Faculty of Materials and Energy Southwest University department of Chemical and Materials Engineering University of Alberta

The aim of this study was to evaluate the strain hardening and hot deformation behavior of asextruded Mg-Zn-Mn （ZM31） magnesium alloy with varying Y contents （0.3, 3.2, and 6 wt%） via compression testing along the extrusion direction at room temperature, 200℃ and 300 ℃. Texture and phases were identified by X-ray diffraction. Alloy ZM31 ＋ 0.3Y consisted of a mixture of fine equiaxed grains and elon- gated grains with 1-phase （Mg3YZno）; alloy ZM31 ＋ 3.2Y contained 1-phase and W-phase （Mg3Y2Zn3）; alloy ZM31 ＋ 6Y had long-period stacking-ordered （lPSO） X-phase （Mg12YZn） and Mg24Y5 particles. With increasing Y content the basal texture became weakened significantly. While alloys ZM31 ＋ 0.3Y and ZM31 ＋ 3.2Y exhibited a skewed true stress-true stain curve with a three-stage strain hardening feature caused by the occurrence of {1072} extension twinning, the true stress-true stain curve of alloy ZM31 ＋ 6Y was normal due to the dislocation slip during compression. With increasing temperature the extent of skewness decreased. While the compressive yield stress, ultimate compressive stress, strain hardening exponent, and hardening capacity all decreased as the temperature increased, the retention of the high- temperature deformation resistance increased with increasing Y content mainly due to the presence of thermally-stable lPSO X-ohase.

关键词： Magnesium alloy Yttrium effect Temperature effect Strain hardening I and W-phase lPSO X-phase

Magneto-Impedance Effect of Composite Wires Prepared by Chemical Plating under dC Current

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Nano-Micro letters 2014年第3期6卷 227-232页

作者： d.l.chen X.li H.l.Pan H.Y.luan Z.J.Zhao department of Physics Engineering Research Center for Nanophotonics & Advanced Instrument Ministry of Education East China Normal University

CuBe composite wires of 100 μm in diameter coated with a layer of NiCoP were prepared by a chemical plating method under dC current(CPUdC). The influences of dC current on coating morphology,deposition rate, composition, giant magneto-impedance(GMI) effect and magnetic properties were *** was shown that the circumferential domain structure of coating layer was induced by the dC current going through the wires. A maximum GMI ratio of 870% was obtained in the composite wire prepared under 150 m A and tested at 180 k Hz. It is 30 times higher than that of the composite wire plated in the same condition by conventional chemical plating method, indicating that CPUdC is an easy and effective approach to obtain composite wires and its applications will be further extended on magnetic sensors.

关键词： GMI Chemical plating Magnetic properties

Adiabatic shear instability in a titanium alloy:Extreme deformation-induced phase transformation,nanotwinning,and grain refinement

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Journal of Materials Science & Technology 2023年第19期150卷 104-113页

作者： X.R.Guan Q.chen S.J.Qu G.J.Cao H.Wang A.H.Feng d.l.chen School of Materials Science and Engineering Tongji UniversityShanghai 201804China Southwest Technology and Engineering Research Institute Chongqing 400039China Shanghai Key laboratory of d&A for Metal-Functional Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China Key laboratory for light-weight Materials Nanjing Tech UniversityNanjing 210009China Interdisciplinary Center for Additive Manufacturing School of Materials and ChemistryUniversity of Shanghai for Science and TechnologyShanghai 2000093China department of Mechanical and Industrial Engineering Toronto Metropolitan University(formerly Ryerson University)TorontoON M5B 2K3Canada

Increasingly harsh service conditions place higher requirements for the high strain-rate performance of titanium *** shear band(ASB),a phenomenon prone to dynamic loading,is often accom-panied by catastrophic ***,it is unclear how the internal nanostructures are related to shear *** we report detailed microstructural evolution in the ASB of a titanium alloy via in-depth focused ion beam(FIB),transmission Kikuchi diffraction(TKd),and high-resolution transmission electron microscope(HRTEM)analyses,with the deformation instability phenomenon discussed from the energy *** ASB interior undergoes multifaceted changes,namely deformation-induced beta-to-alpha transformation and deformation-induced martensitic transformation to form substantially refined and heterogeneous ***,two types of extremely fine twins are identified to occur within both nano-sized martensite and alpha *** critical plastic work representing the onset of adiabatic shear instability and dynamic equilibrium is observed to be constant for a specific structure in the same deformation *** energy analysis could be extended to other materials subjected to high strain-rate dynamic deformation.

关键词： Adiabatic shear instability deformation-induced phase transformation deformation-induced nanotwinning dynamic recovery Energy analysis

Microstructure and mechanical properties of Mg-to-Al dissimilar welded joints with an Ag interlayer using ultrasonic spot welding

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Journal of Magnesium and Alloys 2020年第2期8卷 552-563页

作者： H.Peng d.l.chen X.F.Bai P.Q.Wang d.Y.li X.Q.Jiang College of Engineering and Technology Southwest UniversityTiansheng Road 2Beibei DistrictChongqing 400715China department of Mechanical and Industrial Engineering Ryerson University350 Victoria StreetTorontoOntario M5B 2K3Canada School of Materials and Energy Southwest UniversityTiansheng Road 2Beibei DistrictChongqing 400715China department of Chemical and Materials Engineering University of AlbertaEdmontonAlberta T6G 1H9Canada

lightweight ZEK100-0 Mg alloy and A16022-T43 Al alloy with an Ag interlayer were joined via ultrasonic spot welding(USW),focusing on the microstructural change and tensile lap shear strength of the welded joints in relation to welding ***/Al interface was superseded by Mg/Ag and Al/Ag interfaces,and unfavorable Mg门A-intermetallic compound was *** foil was observed to be intact in the nugget center,while it was broken or dissolved at the nugget edge at high welding energy *** diffusion layer at the Mg/Ag interface consisted of two distinctive sub-layers:Mg3Ag intermetallic compound adjoining Ag foil,and Mg3Ag-l-Mg eutectic structure adjacent to *** a thin diffusion layer consisting mainly of Ag3Al occurred al lhe Al/Ag *** tensile lap shear strength first increased,reached its peak value,and then decreased with increasing welding *** shear strength achieved in the present study was〜31%higher than that of the joint without *** failure occurred at all energy levels,with Ag foil particles or fragments being stuck on both Mg and Al sides due to its intense interaction with Mg and Al via accelerated diffusion during *** results obtained pave the way for the challenging dissimilar welding between Mg and Al alloys.

关键词： Magnesium alloy Aluminum alloy Ultrasonic spot welding Ag interlayer Microstructure Tensile lap shear strength

Influence of an Electronic Field on the GMI Effect of Fe-based Nanocrystalline Microwire

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Nano-Micro letters 2013年第1期5卷 13-17页

作者： Q.Zhang d.l.chen X.li P.X.Yang J.H.Chu Z.J.Zhao Key laboratory of Polar Materials and devices Ministry of EducationDepartment of Electronic EngineeringEast China Normal University Engineering Research Center for Nanophotonics & Advanced Instrument Ministry of EducationDepartment of PhysicsEast China Normal University

In this work, a Fe-based nanocrystalline microwire of 20 mm in length and 25 μm in diameter was placed in the center of a 316 stainless steel pipe. The pipe was 500 μm in diameter and a little shorter than the microwire. A series of voltages were applied on the pipe to study the influence of the electrical field on the Giant-Magneto-Impedance(GMI) effect of the microwire. Experimental results showed that the electronic field between the wire and the pipe reduced the hysteresis of the GMI effect. The results were explained based on equivalent circuit and eddy current consumptions analysis.

关键词： GMI Eddy consumptions Electronic field Equivalent circuit