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Microstructure and mechanical properties of TiAl/TiAl joints brazed with a newly developed Ti–Ni–Nb–Zr quaternary filler alloy

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Progress in Natural Science:Materials International 2022年第6期32卷 758-768页

作者： H.S.Ren Y.L.Shang X.Y.Ren Y.J.Jing H.P.Xiong Y.Y.Cheng Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials

A novel Ti-Ni-Nb-Zr quaternary filler alloy with the composition of Ti-(19～25)Ni-(15～25)(Nb+Zr)(wt.%) was designed.The filler alloy was composed of(Ti,Nb)ss,(Ti,Zr,Nb)ss+(Ti,Zr)2Ni,α-Ti and Ti2Ni phases.It was fabricated into filler foil with a thickness of about 45 μm by a rapid solidification technique.The results indicate that the liquidus temperature of the Ti-Ni-Nb-Zr brazing alloy was about 978℃,and the brazing alloy presented excellent wettability on TiAl substrate.The TiAl joint mainly consisted of β/B2 phase,Ti2Al,Ti2AlNi and α2-Ti3Al phases.The diffusion of Al atom from base metal to brazed seam led to the formation of Ti2Al and Ti2AlNi.Considering that no previously references on XRD pattern of Ti2AlNi compound can be found,Ti2AlNi cast alloy specimen was specially prepared and XRD peaks were specially labeled.The micro-hardness and bending strength tests of the Ti2AlNi phase were carried out,and the results were 761 HV and 192 MPa,respectively.The brazing parameters of 1010 ℃/10 min offered the joint shear strength of 280 MPa at room temperature,and the joints exhibited tensile strength of 372 MPa at room temperature and 340 MPa at 750 ℃,indicating that the newly developed filler alloy could offer a stable high-temperature strength.

关键词： TiAl Brazing Filler alloy Microstructure mechanical properties

Microstructures, mechanical properties, corrosion, and biocompatibility of extruded Mg-Zr-Sr-Ho alloys for biodegradable implant applications

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Journal of Magnesium and Alloys 2023年第1期11卷 110-136页

作者： Faisal Kiani Jixing Lin Alireza Vahid Khurram Munir Cuie Wen Yuncang Li School of Engineering RMIT UniversityMelbourneVictoria 3001Australia School and Hospital of Stomatology Wenzhou Medical UniversityWenzhou 325027China Institute for Frontier Materials Deakin UniversityGeelongVictoria 3217Australia

In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of different concentrations of Ho on the microstructural characteristics,tensile and compressive properties,corrosion resistance,and biocompatibility were investigated.The microstructures of the extruded Mg-1Zr-0.5Sr-xHo(x=0.5,1.5,and 4 wt.%)alloys consisted ofα-Mg matrix,fineα-Zr particles,and intermetallic phase particles of Mg_(17)Sr_(2) and Ho_(2)Mg mainly distributed at the grain boundaries.Extensive{1012}tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho.Further addition of Ho to 4 wt.%resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg_(17)Sr_(2) particles.The evolution of a rare earth(RE)texture was observed with the Ho addition,which resulted in the weakened basal and prismatic textures.Furthermore,a drastic increase of 200%in tensile elongation and 89%in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%,respectively.The tension-compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures.Corrosion analysis of the extruded Mg-Zr-Sr-Ho alloys revealed the presence of pitting corrosion.A minimum corrosion rate of 4.98 mm y^(−1) was observed in Mg-1Zr-0.5Sr-0.5Ho alloy.The enhanced corrosion resistance is observed due to the presence of Ho_(2)O_(3) in the surface film which reduced galvanic effect.The formation of a stabilized surface film due to the Ho_(2)O_(3) was confirmed through the electrical impedance spectroscopy and XPS analysis.An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.

关键词： Mg-Zr-Sr-Ho alloy mechanical properties Corrosion Cytotoxicity EBSD Electrical impedance spectroscopy Potentiodynamic polarization

Effect of Extrusion Temperature on the mechanical properties and Corrosion Behavior of LZ91 Alloys

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Acta Metallurgica Sinica(English Letters) 2023年第11期36卷 1822-1832页

作者： Xuejian Wang Huaqiang Xiao Keqiang Su Bo Lin Tongmin Wang Enyu Guo School of mechanical Engineering Guizhou UniversityGuiyang550000China Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Ningbo Institute of Dalian University of Technology Ningbo315000China

Microstructural observations,tensile tests,potentiodynamic polarization measurements,and corrosion morphology examinations are conducted to investigate the effect of extrusion temperature on the mechanical properties and corrosion behavior of LZ91 alloys.The results show that the tensile strength of the LZ91 alloy is increased by 86 MPa after extrusion at 25℃.Meanwhile,the corrosion resistance is improved by about 2.7 times,and the maximum corrosion depth is decreased by 60μm.The increase in the tensile strength can be mainly attributed to theα-Mg precipitate strengthening inβ-Li.The improvement of the corrosion resistance is due to the fact that the nano-sized MgLiZn and refinedα-Mg precipitates inβ-Li weaken the effect of the cathodic phase on micro-galvanic corrosion,thereby decreasing the cathodic current density and local corrosion susceptibility.However,when the extrusion temperature is increased to 300°C,the corrosion rate is significantly accelerated due to the increase of the micro-galvanic corrosion caused byα-Mg precipitate coarsening at high temperatures.

关键词： Mg-Li alloy Extrusion temperature mechanical properties Corrosion behavior

On mechanical properties of nanocomposite hydrogels:Searching for superior properties

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Nano Materials Science 2022年第2期4卷 83-96页

作者： Wenjin Xing Youhong Tang Institute for NanoScale Science and Technology College of Science and EngineeringFlinders UniversitySouth Australia 5042Australia

Nanocomposite hydrogels are the combination of known components that are a hydrogel and nanometre-sized fillers,typically leading to improved mechanical properties or new functionalities.With simplicity of design and ease of synthesis,recent advances have highlighted that this family of hydrogels holds the significant promise of application in diverse biomedical and engineering fields.The elaborate design and investigation as well as suitable application of nanocomposite hydrogels require the synergy of mechanics,materials science,engineering,and biology.Despite similarities in design and fabrication,the data of mechanical properties for nanocomposite hydrogels scatter in a large space.It is worthwhile comparing various nanocomposite hydrogels for similarities and differences in mechanical properties to aid in designing novel hydrogels with extreme properties,and guide practical applications.This review aims to fill,in the literature,the missing gap of addressing mechanical measurement methods and comparison of mechanical properties in this ever-evolving broad area of research.Finally,the challenges and future research opportunities are highlighted.

关键词： Hydrogel Nanofillers mechanical properties Nanocomposite Design Characterisation

The aging behavior,microstructure and mechanical properties of AlN/AZ91 composite

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镁合金学报(英文) 2023年第7期11卷 2458-2468页

作者： Yunxia Sun Changlin Yang Bin Zhang Jianfeng Fan Hongxiang Li Tianhao Zhao Jing Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’anShaanxi 710072PR China Yangtze River Delta Research Institute of NPU TaicangJiangsu 215400PR China Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024PR China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083PR China

Microstructure evolution and mechanical properties of the aging treated AlN/AZ91 composites were systematically investigated by optical microscopy(OM),high resolution scanning electron microscopy(HRSEM)with an energy dispersive spectrum(EDS),and high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM).The results show that the higher fracture elongation(14±1%)and ultimate tensile strength(275±6 MPa)were simultaneously obtained in the peak-aged AlN/AZ91 composites.Comparied with AZ91 matrix alloy,the strength was increased by about 44%and the elongation was approximately five times higher,which mainly attributed to the precipitation of nano-sizedγ-Mg_(17)Al_(12)phase and the activation of non-basal slip systems induced by in-situ AlN particles at room temperature.However,the in-situ formation of AlN reinforcements consumed part of Al element in the matrix alloy,which resulted into the volume fraction decreasing ofγ-Mg_(17)Al_(12)precipitates,and then the age hardening and strengthening efficiency were reduced in the AlN/AZ91 composites.On the other hand,the mismatch of thermal expansion coefficient between AlN particles and AZ91 matrix generated high density dislocations around AlN particles,which promoted the precipitation ofγ-Mg_(17)Al_(12)phase,and then the peak aging time and temperature were decreased.

关键词： Magnesium matrix composites In-situ AlN particles Aging behavior Microstructure mechanical properties

Effect of Ti Addition on Microstructure Evolution and mechanical properties of Al_(18)Co_(13)Cr_(10)Fe_(14)Ni_(45) Eutectic High-Entropy Alloys

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金属学报:英文版 2023年第9期36卷 1493-1501页

作者： Jia-Qi Zheng Ming-Liang Wang Wen-Na Jiao Long-Jiang Zou Yan Di Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian116024China

A series of new(Al_(18)Co_(13)Cr_(10)Fe_(14)Ni_(45))(100−x)Tix(x=0,0.5,1)eutectic high-entropy alloys(EHEAs)were designed and prepared with the aid of empirical parameter calculations and JMatPro software predictions.The effects of Ti addition on the microstructures,phase structures,and mechanical properties of Al_(18)Co_(13)Cr_(10)Fe_(14)Ni_(45) EHEA were investigated.The results show that(Al_(18)Co_(13)Cr_(10)Fe_(14)Ni_(45))_((100−x))Ti_(x)(x=0,0.5,1)EHEAs are composed of the FCC and B2 phases.With the increase in Ti content,the strength of the EHEAs increases.The volume fraction of the FCC phase decreases,and the volume fraction of B2 phase increases;the size of nanoprecipitates within the B2 phase decreases and the number of them increases,which could be responsible for the high strength due to the addition of Ti.Among them,(Al_(18)Co_(13)Cr_(10)Fe_(14)Ni_(45))99.5Ti0.5 alloy exhibited excellent properties with yield strength,ultimate tensile strength,and ductility of 690 MPa,1065 MPa,and 9.18%,respectively.

关键词： High-entropy alloys Eutectic Microstructure mechanical properties

Optical,thermal,and mechanical properties of(Y_(1−x)Scx)_(2)O_(3)transparent ceramics

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Journal of Advanced Ceramics 2022年第6期11卷 901-911页

作者： Changliang YANG Jiquan HUANG Qiufeng HUANG Zhonghua DENG Yun WANG Xiaoyun LI Zehua ZHOU Jian CHEN Zhuguang LIU Wang GUO College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350117China Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

Sesquioxides such as Y_(2)O_(3)and Sc_(2)O_(3)are important optical materials,but the fabrication of their transparent ceramics remains a challenge due to the ultra-high melting point of over 2400℃.In this work,a series of(Y_(1−x)Scx)_(2)O_(3)transparent ceramics were successfully fabricated by a simple vacuum sintering process without any sintering additives,and the effect of scandium(Sc)content(x)on the crystal structure and optical/thermal/mechanical properties was evaluated.Y_(2)O_(3)and Sc_(2)O_(3)form a complete solid solution with a cubic bixbyite structure.The formation of(Y_(1−x)Scx)_(2)O_(3)solid solution promotes the densification of ceramics,leading to the realization of high transparency close to the theoretical transmittance over a wide wavelength range of 0.35–8μm.In particular,the in-line transmittance in the range of 0.6–6μm remains above 80%for(Y_(1−x)Scx)_(2)O_(3)with x=0.23–0.31,while the pristine Y_(2)O_(3)and Sc_(2)O_(3)are opaque.Moreover,the mechanical properties including Vickers hardness(HV),fracture toughness(KIC),and biaxial flexural strength(δb)are evidently enhanced due to the solid solution strengthening,while the thermal conductivity(k)is reduced due to the reduction of photon free path.This study demonstrates that forming of solid solution is a facile and universal approach for preparing sesquioxide transparent ceramics with high optical and mechanical quality.

关键词： Y_(2)O_(3) Sc_(2)O_(3) solid solution transparent ceramics thermal conductivity mechanical properties

Microstructures and mechanical properties of a New Multi-functional 460 MPa Grade Construction Structural Steel

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Acta Metallurgica Sinica(English Letters) 2022年第7期35卷 1131-1142页

作者： Zhenye Chen Zhangguo Lin Jianjun Qi Yang Feng Liqing Chen Guodong Wang State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China User Technology Department Technology Research Institute of HBISShijiazhuang 050000China

This article reports a new generation of Q460 multi-functional construction structural steel,which has high strength(yield strength larger than 460 MPa),excellent toughness(higher than 110 J/cm^(2) at-60 ℃),lower yield ratio(lower than 0.8),good fire resistance(yield strength at 600 ℃ larger than two-thirds of its room-temperature yield strength)and better corrosion resistance.The eff ects of finish cooling temperature(FCT)on the microstructure and properties were studied by scanning electron microscopy(SEM),transmission electron microscopy(TEM),emission electron probe micro-analysis(EPMA),electron backscattering diff raction(EBSD),tensile tester,impact tester,periodic immersion cycle acceleration test and electrochemical experiment.The results show that the strength and toughness are simultaneously improved by decreasing the FCT due to more lath-like bainite with large number of dislocations,refined martensite/austenite(M/A)with higher carbon concentration and increased high angle boundaries.In addition,the fire resistance of the newly developed Q460 steel is obviously better than the conventional one,which is mainly due to non-recrystallized lath-like bainite with high dislocation density at elevated temperature.The corrosion resistance of the new Q460 steel is also improved due to the addition of Cu and Cr.

关键词： Construction structural steel Thermo-mechanical controlled processing(TMCP) Finish rolling temperature Microstructure mechanical properties

Controlling the mechanical properties and corrosion behavior of biomedical TiZrNb alloys by combining recrystallization and spinodal decomposition

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Journal of Materials Science & Technology 2022年第15期110卷 227-238页

作者： Pengfei Ji Bohan Chen Shuguang Liu Bo Li Chaoqun Xia Xinyu Zhang Mingzhen Ma Riping Liu State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China School of Materials Science and Engineering Research Institute for Energy Equipment MaterialsHebei University of TechnologyTianjin 300130China Beijing Chunlizhengda Medical Instruments Co. Ltd.Beijing 101112China

Excellent comprehensive mechanical properties and corrosion resistance of TiZrNb equiatomic ratio medium-entropy alloy were obtained through recrystallization and spinodal decomposition.In addition to solid solution strengthening and recrystallization,the excellent mechanical properties can also be attributed to the hindering effect of nanoprecipitation formed via spinodal decomposition on the movement of dislocations.The high atomic arrangement density due to spinodal decomposition reduces the surface energy of the alloy passivation film,thereby increasing the activation energy of dissolution and the bonding energy between atoms,which improve the corrosion resistance and stability of the alloy passivation film.This work provides a new strategy to control the mechanical properties and corrosion resistance by combining recrystallization and spinodal decomposition.

关键词： Titanium Zirconium mechanical properties Corrosion resistance Passive films