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Effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging

International Journal of Minerals,Metallurgy and Materials 2015年第7期22卷 721-728页

作者： Wei Gu Jing-yuan Li yi-de wang School of Materials Science and Engineering University of Science and Technology Beijing

The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation （GND） density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 μm- 80 μm separate into fine equiaxed grains of 20μm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83 × 10^13 to 4.40 × 10^11 m^-2 in grains with 〈111〉 fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone （PFZ） are facilitated due to the eroding activity of the Graft etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference.

关键词： aluminum alloys low-angle grain boundaries dislocation structure aging dislocation density

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Mechanism of hot-rolling crack formation in lean duplex stainless steel 2101

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International Journal of Minerals,Metallurgy and Materials 2016年第4期23卷 425-433页

作者： Zhi-hui Feng Jing-yuan Li yi-de wang School of Materials Science and Engineering University of Science and Technology Beijing

The thermoplasticity of duplex stainless steel 2205（DSS2205） is better than that of lean duplex steel 2101（LDX2101）, which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase ratio, and recrystallization dependence of the deformation compatibility of LDX2101 and DSS2205 were investigated using optical microscopy（OM）, electron backscatter diffraction（EBSD）, Thermo-Calc software, and transmission electron microscopy（TEM）. The results showed that the phase-ratio transformations of LDX2101 and DSS2205 were almost equal under the condition of increasing solution temperature. Thus, the phase transformation was not the main cause for the hot plasticity difference of these two steels. The grain size of LDX2101 was substantially greater than that of DSS2205, and the microhardness difference of LDX2101 was larger than that of DSS2205. This difference hinders the transfer of strain from ferrite to austenite. In the rolling process, the ferrite grains of LDX2101 underwent continuous softening and were substantially refined. However, although little recrystallization occurred at the boundaries of austenite, serious deformation accumulated in the interior of austenite, leading to a substantial increase in hardness. The main cause of crack formation is the microhardness difference between ferrite and austenite.

关键词： duplex stainless steel hot rolling crack formation thermoplasticity grain size precipitates softening mechanisms

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Recent Progress on Metal–Organic Framework and Its derivatives as Novel Fire Retardants to Polymeric Materials

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Nano-Micro Letters 2020年第12期12卷 173-193页

作者： Jing Zhang Zhi Li Xiao‑Lin Qi de‑yi wang IMdeA Materials Institute C/Eric Kandel 228906 GetafeMadridSpain Universidad Politécnica de Madrid E.T.S.de Ingenieros de Caminos28040 MadridSpain China‑Spain Collaborative Research Center for Advanced Materials School of Materials Science and EngineeringChongqing Jiaotong UniversityChongqing 400074People’s Republic of China

High flammability of polymers has become a major issue which has restricted its ***,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,have been intensively employed as novel fire retardants(FRs)for a variety of polymers(MOF/polymer).The MOFs possessed abundant transition metal species,fire-retardant elements and potential carbon source accompanied with the facile tuning of the structure and property,making MOF,its derivatives and MOF hybrids promising for fire retardancy *** recent progress and strategies to prepare MOF-based FRs are emphasized and *** fire retardancy mechanisms of MOF/polymer composites are explained,which may guide the future design for efficient MOF-based ***,the challenges and prospects related to different MOFbased FRs are also discussed and aim to provide a fast and holistic overview,which is beneficial for researchers to quickly get up to speed with the latest development in this field.

关键词： Metal–organic frameworks Hybrids Polymers Composites Fire retardancy

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Preparation of AlN thin films for film bulk acoustic resonator application by radio frequency sputtering

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第3期10卷 464-470页

作者： Kan LI Hao JIN de-miao wang yi-fei TANG department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

Aluminum nitride （AlN） thin films with high c-axis orientation have been prepared on a glass substrate with an Al bottom electrode by radio frequency （RF） reactive magnetron sputtering. Based on the analysis of Berg＇s hysteresis model, the improved sputtering system is realized without a hysteresis effect. A new control method for rapidly depositing highly c-axis oriented AlN thin films is proposed. The N2 concentration could be controlled by observing the changes in cathode voltage, to realize the optimum processing condition where the target could be fixed stably in the transition region, and both stoichiometric film composition and a high deposition rate could be obtained. Under a 500 W RF power of a target with a 6 cm diameter, a substrate temperature of 450 ℃, a target-substrate distance of 60 mm and a N2 concentration of 25%, AlN thin film with preferential （002） orientation was deposited at 2.3 μm/h which is a much higher rate than previously achieved. Through X-ray diffraction （XRD） analysis, the full width at half maximum （FWHM） of AlN （002） was shown to be about 0.28°, which shows the good crystallinity and crystal orientation of AlN thin film. With other parameters held constant, any increase or decrease in N2 concentration results in an increase in the FWHM of AlN.

关键词： Aluminum nitride (A1N) Piezoelectric thin film Radio frequency (RF) reactive sputtering Preferred orientation,Film bulk acoustic resonator (FBAR)

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Influence of Al-Si additions on mechanical properties and corrosion resistance of Mg-8Li dual-phase alloys

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Journal of Iron and Steel Research International 2017年第4期24卷 426-429页

作者： Zi-long Zhao Xue-gang Xing yi Luo yi-de wang Wei Liang College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024ShanxiChina Shanxi Key Laboratory of Advanced Magnesium based Materials Taiyuan 030024ShanxiChina Institute of Applied Mechanics and Biomedical Engineering Taiyuan University of TechnologyTaiyuan 030024ShanxiChina

Sheet samples of Mg-8Li,Mg-8Li-3Al,Mg-8Li-3AlSi and Mg-8Li-5AlSi alloys were obtained by hot *** microscope,microhardness tester,nanoindentor,X-ray diffractometer and electrochemical analyzer were adopted to investigate the microstructures,micro-mechanical properties and corrosion *** was preheated to 150°C before rolling process,and rolling reduction designed was about20% per pass with a total rolling reduction of 84%.The rolled plates were annealed at 200°C for 120 *** tensile tests were performed at room *** results showed that both the strength and corrosion resistance of theα＋βdual-phase of Mg-Li alloy were significantly improved with adding Al-Si *** strength enhancement was attributed to the solid solution of Al into theα-Mg matrix and into theβ-Li matrix as well as to the precipitation strengthening of Mg2 Si ***,the dendrite grains ofα-Mg transformed to equiaxed ones with addition of Al into alloy Mg-Li.

关键词： Mg-8Li dual-phase alloy Mechanical property Corrosion resistance Hardness Rolling

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SYNERGISTIC EFFECTS OF NOVOLAC-BASED CHAR FORMER WITH A PHOSPHORUS/NITROGEN-CONTAINING FLAME RETARD ANT IN POLYAMIde 6

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Chinese Journal of Polymer Science 2012年第1期30卷 72-81页

作者： Wei-cheng Xiong Li Chen de-yi wang Fei Song Yu-zhong wang Center for degradation an-d Flame--Retardant Polymeric Materials College of-Chemistry State Key Laboratory of Polymer Materials Engineering National Engineering Laboratory of Eco-Friendly Polymeric Materials （Sichuan） Sichuan University Chengdu 610064 China

The synergistic effect of phosphorus oxynitride（PON） with a novolac-based char former modified by salification （NA-metal salt） on the flame retardance of polyamide 6（PA6） was *** this purpose,various flame-retardant PA6 systems were melt-compounded with PON,PON/NA,PON/NA-V_2O_5 and PON/NA-Fe_2O_3,and their flame retardance was evaluated by measuring the limiting oxygen index（LOI） values and UL-94 vertical burning *** results showed that,compared with the PA6/PON/NA system,the combination of two char formers（NA-V_2O_5,NA-Fe_2O_3） with PON could obviously improve the char formation and flame retardance of *** flame retardance and cone calorimetric analyses showed the stronger synergism as well as the better flame retardant performance of PON/NA-Fe_2O_3 flame retardant system. The effects of different char formers on the flame retardance and thermal stability of this system were also discussed.

关键词： Polyamide Flame retardance Novolac resin Synergistic effect

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An Overview of the Flame Retardants for Poly(vinyl chloride):Recent States and Perspective

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Chinese Journal of Chemistry 2020年第12期38卷 1870-1896页

作者： Ye-Tang Pan Yongshuai Yuan de-yi wang Rongjie Yang Nation al Engineering Technology Research Center of Flame Retardant Materials School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China IMdeA Materials Institute C/Eric Kondel228906 GetofeMadridSpain

As a versatile star product,poly(viny chloride)(PVC)has kept active in our dily lif all through since it was ***,the severe fire hazard andheavy smoke produced during combustion,particularly the extensively used flexible PC product,have been putzig manufacturers and researchers *** the last decade,multifarious ftame retardants and smoke suppressants were developed for PVC materias.n this review combined literaturewith the results based on the research from our group,recent emerged fame retardants and smoke suppressants for PVC are ***,theflame retardant mechanisms and experimental analysis resuts are described to understand the relationship between characters of fame retardants (in-cluding chemical compositions,structures or morphologies)and fire performance of the *** potential substitutes for traditional harmfulflame retardant antimony trioxide are discussed aiming to the emphasis on increasing prominent environmental *** partcular,one section isdedicated to new approaches for the preparation of novel environmentally friendly and high-effciency fame *** hoped that ths review wilnot only summarine the new emerged fame retardants and smoke suppressants for PVC,but also provide the new trend to prompt sequent explorationin both academic research and industrial application.

关键词： smoke prompt versatile

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Influence of hot rolling on the microstructure of lean duplex stainless steel 2101

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International Journal of Minerals,Metallurgy and Materials 2019年第10期26卷 1266-1273页

作者： Zhi-jun Gao Jing-yuan Li Zhi-hui Feng yi-de wang School of material science and engineering University of Science and Technology BeijingBeijing100083China Institute of Engineering Technology University of Science and Technology BeijingBeijing100083China

In this work, the microstructure and the strain partitioning of lean duplex stainless steel 2101 (LDX 2101) during different hot-rolling processes are investigated by optical microscopy and electron-backscattered diffraction (EBSD). The results show that the LDX 2101 exhibits poor thermoplasticity at high temperature. The four-pass hot-rolled plates show fewer edge-cracking defects and superior thermoplasticity compared with the two-pass hot-rolled plates prepared at different temperature. The phase boundary is the weakest site in the LDX 2101. The cracks are initiated and propagated along the phase boundaries during the hot-rolling process. According to the EBSD analysis, the increase of the hot-rolling pass can dramatically improve the strain distribution in ferrite and austenite phases and promote the strain transmission in the constituent phases, thereby improving the coordinated deformation ability of the two phases. This effect further in- creases the thermoplasticity and reduces the formation of edge cracks in LDX 2101.

关键词： lean duplex stainless steel hot-rolling process thermoplasticity strain distribution

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Work Hardening Behavior and Stability of Retained Austenite for Quenched and Partitioned Steels

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Journal of Iron and Steel Research International 2016年第2期23卷 130-137页

作者： Cun-yu wang ying CHANG Jie YANG Wen quan CAO Han DONG yi-de wang Central Iron and Steel Research Institute Beijing 100081China Taiyuan Iron and Steel Group Co. Ltd.Taiyuan 030003ShanxiChina National Key Laboratory of Industrial Equipment Structural Analysis School of Automotive EngineeringDalian University of TechnologyDalian 116024LiaoningChina Society of Automotive Engineers of China Beijing 100055China

Both microstrueture and mechanical properties of low alloy steels treated by quenching and partitioning （Q＆P） process were examined. The mixed microstructure of martensite and large-fractioned retained austenite （about 27.3%） was characterized and analyzed, excellent combinations of total elongation of 19% and tensile strength of 1 835 MPa were obtained, and three-stage work hardening behavior was demonstrated during tensile test. The en hanced mechanical properties and work hardening behavior were explained based on the transformation induced plas ticity effect of large fractioned austenite.

关键词： Q&P process work hardening retained austenite martensite mechanical property TRIP effect

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Effect of Organo-Modified Nanosepiolite on Fire Behaviors and Mechanical Performance of Polypropylene Composites

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Chinese Journal of Chemistry 2015年第2期33卷 285-291页

作者： Junhao Zhang Sergio de Juan Antonio Esteban-Cubillo Julio Santarén de-yi wang Madrid Institute for Advanced Studies of Materials(IMdeA-Materials) C/Eric Kandel2Getafe(Madrid)28906Spain Tolsa S.A.R.&D.department Carretera de Madrid a Rivas Jarama3528031 MadridSpain

The objective of the study was to investigate the effect of the organo-modified nanosepiolite(ONSep)on improving the fire safety of polypropylene(PP).The composites based on PP,flame retardant master batch(MB-FR,25 wt%PP+50 wt%decabromodiphenyl ether(DBDPE)+25%antimony trioxide(ATO))and ONSep were prepared via melt *** results of the limiting oxygen index(LOI)and vertical burning rating(UL-94)test indicated that PP/40 wt%MB composites had no rating with seriously dripping phenomenon,while the LOI value was only ***,as 4 wt%ONSep was added in PP/40 wt%MB composites,the composites achieved UL94 V-0 rating and the LOI value was *** comparison,PP/50 wt%MB composites could not reach the V-0 rating *** TGA results revealed that the addition of ONSep enhanced the thermal stability of the PP/MB-FR *** cone calorimeter results indicated that the heat release rate,average mass loss rate,smoke production rate and smoke temperature of the PP/40 wt%MB-FR/4 wt%ONSep composites decreased in comparison with those of PP/40 wt%MB-FR ***,the Young modulus and impact strength were also much better improved with the increase of ONSep ***,the synergistic flame retardancy of ONSep in PP/MB-FR matrix significantly containing a halogen based flame retardant(DBDPE)significantly improved the fire safety and mechanical properties of the composites,and allowed to decrease the total amount of brominated fire retardants.

关键词： nanosepiolite polypropylene flame retardancy heat release rate

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