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Microstructure and mechanical properties of repair welds of low-pressure sand-cast Mg?Y?RE?Zr alloy by tungsten inert gas welding

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Journal of Magnesium and Alloys 2022年第1期10卷 195-209页

作者： Xin Tong Guohua Wu Liang Zhang Yingxin Wang Wencai Liu Wenjiang Ding National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The sand castings of Mg-Y-RE-Zr series alloys are widely utilized in the large scales and complex shapes in the aerospace industry,as a result of which there are always some cast defects in the products. In this study, the feasibility of repair welding of sand-cast Mg-4 Y-3 RE-0.5 Zr alloy by tungsten inert gas(TIG) welding was scrutinized with different welding currents from 150 to 210 A. The results indicated that defect-free repaired joints with good appearance could be acquired at 170 and 190 A. Interestingly, the grain size of the fusion zone(FZ) was refined initially and then increased with the linear increment of welding current. Because at the higher heat inputs, although the cooling rate of the molten pool was reduced, substantial constitutional supercooling for the grain refinement was attained after the Zr particles were transformed into Zr solutes. The tensile strength of the repaired joint at 170 A was 195 MPa with the maximum joint efficiency of 87.8%, and the elongation reached to 124.4% of the sand-cast base material(BM). However, serious grain coarsening and continuous eutectic structures generated in heat-affected zone(HAZ) above 190 A resulted in the weakening of the joint due to the brittle intergranular fracture.

关键词： Sand-cast Mg-Y-RE-Zr alloy Repair welding Microstructure Tensile properties Fracture behavior

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Effects of V addition on the mechanical properties at elevated temperatures in a γ”-strengthened NiCoCr-based multi-component alloy

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Journal of materials science & Technology 2022年第12期107卷 290-300页

作者： Yunwei Pan Anping Dong Yang Zhou Dafan Du Donghong Wang Guoliang Zhu Baode Sun Shanghai Key Lab of Advanced High-temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Lab of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

Ni Co Cr-based multi-component alloys have drawn much attention due to their exceptional ductility and strain hardening ***,insufficient strength-ductility synergy of NiCoCr alloy has always been an issue that prevents it from extensive *** to our previous research,the precipitation ofγ”phase can significantly improve the strength-ductility synergy of this alloy system at room *** this study,the effects of V addition onγ”phase stability and high-temperature mechanical properties have been explicitly *** results indicate that V addition can stabilize the metastableγ”phase in this alloy system and prevent it from transforming into a stableδphase at grain boundaries upon 650℃aging,resulting in improved mechanical properties at elevated *** specific strength ofγ”-strengthened multi-component NiCoCr-based alloy can reach up to 86.2 MPa gcmat 650℃,which is higher than those of Ni-based superalloys,IN 939 and *** work provides theoretical guidance for the novel design of γ”-strengthened alloy for high-temperature applications.

关键词： Multi-component alloys CALPHAD γ”phase Microstructural evolution High-temperature mechanical properties

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A new insight into LPSO phase transformation and mechanical properties uniformity of large-scale Mg-Gd-Y-Zn-Zr alloy prepared by multi-pass friction stir processing

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Journal of Magnesium and Alloys 2024年第5期12卷 2041-2056页

作者： Xiaohu Guan Wen Wang Ting Zhang Pai Peng Qiang Liu Peng Han Ke Qiao Jun Cai Liqiang Wang Kuaishe Wang School of Metallurgical Engineering National and Local Joint Engineering Research Center for Functional Materials ProcessingXi’an University of Architecture and TechnologyNo.13 Yanta RoadXi’anShaanxi 710055China Xi’an Rare Metal Materials Institute Co.Ltd Xi’an 710016China State Key Laboratory of Metal Matrix Composites School of Material Science and EngineeringShanghai Jiao Tong UniversityNo.800 Dongchuan RoadShanghai 200240China

A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this *** structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was ***,a quantitative relationship between the microstructure and tensile yield strength was *** results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were *** IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute *** severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO *** MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% *** refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP *** particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in *** result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.

关键词： Friction stir processing Multi-pass Mg-Gd-Y-Zn-Zr alloy LPSO phase transformation Mechanical properties

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Achieving grain refinement ofα-Al and Si modification simultaneously by La-B-Sr addition in Al-10Si alloys

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Journal of materials science & Technology 2023年第4期135卷 97-110页

作者： Qun Luo Xingrui Li Qian Li Lingyang Yuan Liming Peng Fusheng Pan Wenjiang Ding State Key Laboratory of Advanced Special Steels&Shanghai Key Laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai UniversityShanghai 200444China National Engineering Research Center for Magnesium Alloy Chongqing UniversityChongqing 400044China National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

As-cast Al-Si alloys always face low ductility because of coarseα-Al grains and large lamellar eutectic *** B-containing refiners and Sr modifiers could refine theα-Al grains and eutectic Si respec-tively,simultaneous addition leads to an invalid effect of Sr because B-containing refiner has a poison-ing effect(PE)on Sr modifier in the Al-10Si-B-Sr *** present work achieves both refinement ofα-Al grains and modification of Si merely by the addition of 500 ppm La in Al-10Si-0.02B-0.015Sr alloy,which greatly enhances the ductility and tensile ***-B interaction in the Al-10Si-0.02B-0.015Sr melt results in a consumption of Sr by forming Sr-B intermetallic ***-type calculations reveal that Sr concentration in liquid before eutectic reaction becomes a key parameter to estimate the alloying modification *** addition of La forms lab 6 and thereby releases Sr to protect the Sr modification ***-principles calculations illustrate that both Sr and La are benefi-cial to the formation of twin boundaries in Si particles due to their negative formation energy of twin *** formed lab 6 has a semicoherent interface withα-Al with the orientation relationship of[110]_(lab6)//[110]_(Al) and(111)_(lab6)//(111)_(Al),demonstrating that lab 6 is an efficient nucleation site forα-Al,which contributes to the refinement ofα-Al in the Al-10Si-0.05La-0.02B-0.015Sr *** findings re-veal the micro-mechanism of refinement during the solidification process and develop an effective and simple way to obtain high-performance Al alloys.

关键词： Al-Si casting alloys Si modification Twinning Grain refinement Semicoherent interface

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Effects of Ce content on the modification of Mg_(2)Si phase in Mg-5Al-2Si alloy

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Journal of Magnesium and Alloys 2023年第7期11卷 2299-2311页

作者： Bo Hu Wen-Jie Zhu Zi-Xin Li Seul Bi Lee De-Jiang Li Xiao-Qin Zeng Yoon Suk Choi National Engineering Research Center of Light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China School of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China

The effect of Ce content(0–1.6 wt.%)on the modification of Mg_(2)Si phase in the as-cast Mg-5Al-2Si alloy was *** original Chinese script type Mg_(2)Si phase was refined distinctly and transformed to dispersive block shape gradually by adding Ce *** length of Chinese script type Mg_(2)Si phase was reduced from 110 to 50μm with increasing Ce content to 1.6 wt.%.The results calculated by Pandat software indicated that the added Ce element first combined with Si to form CeSi_(2)phase,which could serve as the heterogeneous nucleation of Mg_(2)Si phase due to the small lattice mismatch of 7.97%.The modification of Mg_(2)Si phase was mainly attributed to the facts that Ce changed the growth steps of Mg_(2)Si phase and CeSi_(2)promoted the nucleation of Mg_(2)Si *** increasing Ce content from 0 wt.%to 1.6 wt.%,the YS,UTS and EL at 150℃were improved from 67.7 MPa,91.2 MPa and 1.6%to 84.2 MPa,128 MPa and 7.5%,respectively.

关键词： Mg-Al-Si alloys Mg_(2)Si modification Heterogeneous nucleation Mechanical properties

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Non-negligible role of gradient porous structure in superelasticity deterioration and improvement of NiTi shape memory alloys

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Journal of materials science & Technology 2024年第19期186卷 48-63页

作者： Yintao Zhang Daixiu Wei Yang Chen Lechun Xie Liqiang Wang Lai-Chang Zhang Weijie Lu Guang Chen State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupWA 6027Australia

Bone-mimicking gradient porous NiTi shape memory alloys(SMAs)are promising for orthopedic im-plants due to their distinctive superelastic functional ***,premature plastic deformation in weak areas such as thinner struts,nodes,and sharp corners severely deteriorates the superelasticity of gradient porous NiTi *** this work,we prepared gradient porous NiTi SMAs with a porosity of 50%by additive manufacturing(AM)and achieved a remarkable improvement of superelasticity by a simple solution treatment *** solution treatment,phase transformation temperatures dropped signif-icantly,the dislocation density decreased,and partial intergranular Ti-rich precipitates were transferred into the *** to as-built samples,the strain recovery rate of solution-treated samples was nearly doubled at a pre-strain of 6%(up to 90%),and all obtained a stable recoverable strain of more than 4%.The remarkable superelasticity improvement was attributed to lower phase transformation tem-peratures,fewer dislocations,and the synergistic strengthening effect of intragranular multi-scale Ti-Ni ***,the gradient porous structure played a non-negligible role in both superelasticity deterioration and *** microstructure evolution of the solution-treated central strut after constant 10 cycles and the origin of the stable superelastic response of gradient porous NiTi SMAs were *** work provides an accessible strategy for improving the superelastic performance of gra-dient porous NiTi SMAs and proposes a key strategy for achieving such high-performance architectured materials.

关键词： Shape memory alloys Superelasticity Gradient porous structure Solution treatment Stable recoverable strain

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Damping performance of SiC nanoparticles reinforced magnesium matrix composites processed by cyclic extrusion and compression

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Journal of Magnesium and Alloys 2023年第5期11卷 1608-1617页

作者： Mahmoud Ebrahimi Li Zhang Qudong Wang Hao Zhou Wenzhen Li National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240PR China School of Mechanical Engineering North University of ChinaTaiyuan 030051PR China Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094PR China School of Materials Science and Engineering Tsinghua UniversityBeijing 10084PR China

This work dealt with the damping performance and its underlying mechanism in SiC nanoparticles reinforced AZ91D composite(SiC_(np)/AZ91D)processed by cyclic extrusion and compression(CEC).It was found that the CEC process significantly affects the damping performance of the composite due to alterations in the density of dislocations and grain boundaries in the matrix *** there would be dynamic precipitation of the Mg17Al12 phase during processing which increases the phase interface and limits the mobility of dislocations and grain *** results also showed that the damping capacity of 1%SiC_(np)/AZ91D composite continuously decreases with adding CEC pass number and it consistently increases with rising the applied *** the first derivative of the tanδ-T curve,the dominant damping mechanism based on test temperature can be divided into three *** three regions are as follows(i)dislocation vibration of the weak pinning points(≤T_(cr)),(ii)dislocation vibration of the strong pinning points(T_(cr)∼T_(V)),and(iii)grain boundary/interface sliding(≥T_(V))

关键词： metal matrix composite SiC nanoparticles Severe plastic deformation Temperature-dependent damping curves Damping mechanism

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The threat of hemorrhage from pelvic fractures:Clinicians seeking new solutions based on biomedical Mg implant

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Journal of Magnesium and Alloys 2025年第4期13卷 1476-1479页

作者： Qinghui Han Xiaonong Zhang Wenhui Wang Kaiyang Wang Tao Wang Trauma Center Tongji HospitalSchool of MedicineTongji UniversityShanghai 200065China State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghaiChina Suzhou Origin Medical Technology Co.Ltd. JiangsuChina College of Biological Science and Medical Engineering Donghua UniversityShanghaiChina

Biodegradable magnesium(Mg)materials offer significant advantages in trauma care due to their degradable nature and superior mechanical *** study reports the first successful use of degradable Mg clips in damage control surgery for pelvic fractures,addressing challenges associated with severe hemorrhage and high mortality rates(30-70%).A 57-year-old male patient with pelvic fractures and traumatic shock underwent open reduction and internal fixation with Mg *** a six-month follow-up,imaging confirmed fracture healing,clip degradation,and no signs of rebleeding or infection,highlighting their effectiveness in precise hemorrhage *** traditional titanium clips,Mg clips degrade over time,eliminating the need for removal and reducing infection *** innovative approach combines Mg clips with conventional gauze packing,offering a more effective and safer alternative for managing pelvic *** large-scale clinical trials are necessary to validate these findings and establish Mg clips as a global standard for pelvic fracture *** portability and functionality hold promise for advancing emergency trauma care.

关键词： Biodegradable Mg Hemorrhage Pelvic fractures Ligation clip

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Enhancing strength and ductility of AlSi10Mg fabricated by selective laser melting by TiB_(2)nanoparticles

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Journal of materials science & Technology 2022年第14期109卷 254-266页

作者： Y.K.Xiao H.Chen Z.Y.Bian T.T.Sun H.Ding Q.Yang Y.Wu Q.Lian Z.Chen H.W.Wang State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China School of Materials Science&Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In the metallic components fabricated by the emerging selective laser melting(SLM)technology,most strategies used for strengthening the materials sacrifice the ductility,leading to the so-called strengthductility *** the present study,we report that the strength and ductility of materials can be enhanced simultaneously by introducing nanoparticles,which can break the trade-off of the metallic *** the case of in-situ nano-TiB_(2)decorated AlSi10Mg composites,the introduced nanoparticles lead to columnar-to-equiaxed transition,grain refinement and texture *** increasing content of nanoparticles,the strength increases ***,the ductility first increases and then *** results show that the ductility is controlled by the competition between the crack-induced catastrophic fracture and ductile fracture associated with dislocation *** first increase of ductility is mainly attributed to the suppression of crack-induced catastrophic fracture when TiB_(2)nanoparticles *** the further increase of TiB_(2)nanoparticles,the subsequent decrease of ductility is mainly controlled by dislocation ***,the materials will exhibit the optimum strength and ductility combination in a certain range of TiB_(2)*** study clarifies the physical mechanism controlling ductility for nano-TiB_(2)decorated Al Si10Mg composites,which provides the insights for the design of structural materials.

关键词： Selective laser melting Aluminium matrix composites Ductility Mechanical behavior Dislocations Cracks

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Determination of multilevel chirality in nickel molybdate films by electron crystallography

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Nano Research 2024年第9期17卷 8571-8577页

作者： Jing Ai Yu Wang Liyuan Li Jianqiang Wang Te Bai Shunai Che Lu Han Sinopec(Shanghai)Research Institute of Petrochemical Technology Co. Ltd.Shanghai 201208China School of Chemical Science and Engineering Tongji UniversityShanghai 200092China School of Chemistry and Chemical Engineering State Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong UniversityShanghai 200240China

Chiral inorganic materials have attracted great attention owning to their unique physical and chemical properties attributed to the symmetry-breaking of their *** inorganic materials can be endowed with chiral geometric configurations from achiral space group crystals through lattice twisting,screw dislocations or hierarchical self-assembled spiral morphologies,showing various characteristic chiral ***,the multilevel chirality in chiral nickel molybdate films(CNMFs)remains to be elaborately *** this paper,we report three hierarchical levels of chirality in CNMFs,spanning from the atomic to the micron scale,including primary helically coiled nanoflakes with twisted atomic crystal lattices,secondary helical stacking of layered nanoflakes,and tertiary asymmetric morphology between adjacent *** findings may enrich the chiral self-assembly structural types and provide valuable insights for the comprehensive analysis path of hierarchical chiral crystals.

关键词： chiral inorganic material nickel molybdate structural analysis transmission electron microscopy electron crystallography

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