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Microstructure and phase transformation of as-cast and annealed Mg–4Zn–1Y alloy containing quasi-crystal phase

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Rare Metals 2015年第4期34卷 239-244页

作者： Yang Yang Kui Zhang Xing-Gang Li Yong-Jun Li ming-long ma Guo-Liang Shi Jia-Wei Yuan State Key Laboratory for Fabrication and Processing of Nonferrous Metals General Research Institute for Nonferrous Metals

By means of optical microscope （OM）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） analyses, the microstructures of as-cast and heat-treated Mg--4Zn-IY （wt%） alloy containing quasi-crystal phase were studied. The microstructure of the as-cast alloy consists of a-Mg solid solution grains, intermetallic particles and eutectic phases （W-phase and 1-phase）, and huge grains with seri- ous dendritic segregation are clearly observed. After heat treatment, phase transformation and dissolution occur in the alloy and many phases remain. When the alloy was treated above 410 ~C, the eutectic phases transform into spherical shape as the I-phase turns to W-phase. After heat treatment for long time, the alloy is over burnt and the W-phase decomposes to Mg-Y binary phase.

关键词： Mg-Zn-Y alloy Heat treatment Microstructure Phase transformation Icosahedral quasi-crystal

Dislocation configuration evolution during extension twinning and its influence on precipitation behavior in AZ80 wrought magnesium alloy

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镁合金学报(英文) 2023年第7期11卷 2442-2457页

作者： Guo-Liang Shi Kui Zhang Xing-Gang Li Yong-Jun Li ming-long ma Jia-Wei Yuan Hong-Ju Zhang State Key Laboratory of Nonferrous Metals and Process Grinm Group Corporation Limited(GRINM)Beijing 100088China GRImaT Engineering Institute Co. Ltd.Beijing 101407China Guobiao(Beijing)Testing and Certification.Co. Ltd.Beijing 101407China

Thermomechanical treatment T10(extension twinning+aging treatment)can largely enhance the precipitation strengthening effect of magnesium *** this study,dislocation structure evolution and precipitation behavior during T10 treatment of an AZ80 extruded bar were analyzed mainly by two-beam diffraction in *** a compressive strain of 1%in the extrusion direction(ED),a typical dislocation configuration,including basal I1 stacking faults(SFs)anddislocations,has been established in extension *** the strain reaches 7%,the volume fraction of extension twins increases to more than 90%at which point high dense I1 SFs anddislocations *** aging for 2 h at 150℃for the 7%strained sample,masses of basal I1 SFs anddislocations remain in the extension twins and can act as effective nucleation sites and solute fast-diffusion channels for continuous ***,the precipitates in extension twins become highly dense.

关键词： magnesium alloy Extension twin Dislocation Stacking fault Precipitation

Homogenization heat treatment of Mg-7.0 wt%Y-1.0 wt%Nd-0.5 wt%Zr alloy

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Rare Metals 2020年第10期39卷 1196-1201页

作者： Jing-Bao Liu Kui Zhang Jing-Tao Han Xing-Gang Li Yong-Jun Li ming-long ma Jia-Wei Yuan Meng Li State Key Laboratory for Fabrication and Processing of Nonferrous Metals Beijing General Research Institute for Nonferrous MetalsBeijing 100088 China School of materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

The microstructures and mechanical properties of Mg-7.0 wt%Y-1.0 wt%Nd-0.5 wt%Zr magnesium alloy were investigated both in as-cast condition and after homogenization heat treatment by differential scanning calorimetry(DSC),optical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM)and hardness *** results indicate that the ascast alloy consists ofα-Mg matrix,Mg24 Y5 and Mg41 Nd5 phases,which are eutectic phases(cubic Y-rich phase).With the increase in homogenization temperature and time,the Mg24 Y5 and Mg41 Nd5 phases are completely dissolved into matrix,and only yttrium of intermetallic compounds leaves around *** homogenization heat treatment,the elements distributed uniformly and the grains grow up not obviously,only yttrium element of intermetallic compounds left around *** optimum homogenization condition is at 537℃for 16 *** mechanical properties are improved after homogenization,with tensile strength ofσb=181 MPa,yielding strength ofσ(0.2)=144 MPa and elongation ofδ=5.5%,which are better than those of as-cast alloy.

关键词： Rare earth magnesium alloy Homogenization Microstructure Hardness

Corrosion behaviors for peak-aged Mg-7Gd-5Y-lNd-0.5Zr alloys with oxide films

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Rare Metals 2016年第10期35卷 758-762页

作者： Quan-Tong Jiang Kui Zhang Xing-Gang Li Yong-Jun Li ming-long ma Guo-Liang Shi Jia-Wei Yuan State Key Laboratory for Nonferrous Metals and Process General Research Institute for Nonferrous MetalsBeijing 100088China

The corrosion behaviors of T5 （225 ℃, 6.5 h） and T6 （460 ℃, 2 h ＋ 225 ℃, 12 h） peak-aged Mg-7Gd- 5Y-1Nd-0.5Zr alloys with oxide films were investigated by optical microscope （OM）, scanning electron microscopy （SEM）, and energy-dispersive spectroscopy （EDS）. The weight loss rates and electrochemical tests were also analyzed. The thicknesses of T5 and T6 oxide films are roughly 0.6 and 1.0 μm, respectively. The components of oxide films mainly consist of O, Mg, Y, Nd, and Gd, and the T6 oxide film results in surfaces with larger peaks than T5 oxide film. In addition, Y, Nd, and Gd peaks are all higher than those of Mg-7Gd-5Y- 1Nd-0.5Zr alloys, but Mg peak is consistently far below than that of the alloys. The specimens could be arranged in de- creasing order of corrosion rates and corrosion current densi- ties： T6 oxide film 〈 T5 oxide film 〈 T6 without oxide film 〈 T5 without oxide film. The oxide films are compact to increase the corrosion resistance for Mg-7Gd-5Y-1Nd-0.5Zr alloys, which will provide a guiding insight into the corrosion and protection of Mg-RE alloys in atmospheric environments.

关键词： Mg-7Gd-5Y-1Nd-0.5Zr alloys Peak-aged Oxide film Corrosion behavior

Microstructure and texture evolution of Mg–7Y–1Nd–0.5Zr alloy sheets with different rolling temperatures

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Rare Metals 2020年第11期39卷 1273-1278页

作者： Jing-Bao Liu Kui Zhang Jing-Tao Han Xing-Gang Li Yong-Jun Li ming-long ma Jia-Wei Yuan Guo-Liang Shi State Key Laboratory for Fabrication and Processing of Nonferrous Metals Beijing General Research Institute for Nonferrous MetalsBeijing100088China School of materials Science and Engineering University of Science and Technology BeijingBeijing100083China

The extruded Mg-7Y-1Nd-0.5Zr(wt%)alloy were performed to the same strain hot rolling with different *** microstructure and texture evolution of the sheets were investigated by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and electron back-scattered diffraction(EBSD).The results indicate that the microstructure becomes homogeneous after hot rolling process and precipitated phase distributes at grain boundaries along rolling *** the increase in rolling temperature,the grains of sheet grow *** sheet rolling at 400℃is composed of recrystallization grains,the necklace of the precipitated phase in the grain boundaries and excessive *** structure of necklace of the precipitated phase is fcc structure with lattice constant of a=0.75 *** rolling temperatures increasing from 400 to 450℃,the content of recrystallized grains in volume fraction with relatively random orientations increases *** with the rolling process at 400℃,the amount of precipitated phases is reduced at the grain boundary,and the precipitated phase begins to appear in the grain interior when rolling at 450℃.The structure of the precipitated phase is fcc with lattice constant of a=2.22 *** recrystallization grains begin to grow in the rolling process at 500℃.The basal texture is obviously produced during the rolling process at 400 and 450℃;however,the basal texture is weak in the rolling process at 500℃.

关键词： Rare earth magnesium alloy Rolling Texture Precipitated phase

Microstructure and corrosion resistance of bone-implanted Mg-Zn-Ca-Sr alloy under different cooling methods

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Rare Metals 2021年第3期40卷 643-650页

作者： He-Ning Liu Kui Zhang Xing-Gang Li Yong-Jun Li ming-long ma Guo-Liang Shi Jia-Wei Yuan Kai-Kun Wang State Key Laboratory of Nonferrous Metals and Process GRINM Group Co.Ltd.Beijing 100088China School of materials Science and Engineering University of Science and Technology BeijingBeijing 100083China GRImaT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

The cooling gradient of Mg-3 Zn-1 Ca-0.5 Sr alloy in cast ingots under different cooling methods(air cooling,warm-water cooling and ice-water-mixture cooling) was examined and the effect of cooling rate on the structure and corrosion properties was *** microstructure of the alloy was composed of α-Mg,Ca_(2) Mg_(6) Zn_(3) and Mg_(17)Sr_(2) *** the solidification cooling rate increased,the grain was refined,Zn and Sr were less segregated,the distributions of Zn and Sr were more uniform,and corrosion rate was found to first increase and then decrease;this contradicts the findings of recent *** cooling rate increasing,the number of corroded microcouples comprising second phase and α-Mg *** α-Mg participates in corrosion,leading to a layered and deep corrosion pit and an increased corrosion ***,as the microstructure became sufficiently dense,the corroded structure protected the deep α-Mg from participating in corrosion,thus reducing the corrosion rate.

关键词： Corrosion Mg-Zn-Ca-Sr Morphology Cooling methods

A porous Eu-PTA/Tb-SSA/ZrO_(2)/ZnZrO_(3) light color adjustable phosphor:Luminescent property and application of warm white LED

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Journal of Rare Earths 2024年第8期42卷 1421-1428,I0001页

作者： Yunxiao ma Chao Linghu ming Yang Hui Yu Xiangting Dong long Xia School of Chemistry and Environmental Engineering Changchun University of Science and TechnologyChangchun130022China School of materials Science and Engineering Harbin Institute of Technology(Weihai)Weihai264209China

Light emitting diode(LED) is the fourth generation lighting source,but it has some shortcomings such as complex chip packaging process and the unbalanced light color of phosphor in long-time *** this study,a kind of Eu-terephthalic acid/Tb-sulfosalicylate/ZrO_(2)/ZnZrO_(3)(Eu-PTA/Tb-SSA/ZrO_(2)/ZnZrO_(3))phosphor with warm white light emission properties was prepared,and the warm white light LED(wWLEDs) was successfully prepared by encapsulating Eu-PTA/Tb-SSA/ZrO_(2)/ZnZrO_(3) phosphors together with 270 nm *** ZrO_(2)/ZnZrO_(3),Tb-SSA/ZrO_(2)/ZnZrO_(3) and Eu-PTA/ZrO_(2)/ZnZrO_(3) samples show blue emission,green emission and red emission under deep ultraviolet(UV,270 nm) excitation,*** Tb-SSA and Eu-PTA are co-doped into ZrO_(2)/ZnZrO_(3) matrix with blue emission to achieve the warm white light emission,and the light color can be adjusted by controlling the doping amount of Eu^(3+)-and Tb^(3+).Through the excitation method of single-component phosphor by the single chip,the complex chip packaging process of w-LED can be *** doping rare earth organic complexes into porous ZrO_(2)/ZnZrO_(3) matrix,the problems of the light color unbalanced of phosphor and the low luminescence intensity of rare earth doped metal oxides composites can be solved.

关键词： Eu-PTA/Tb-SSA/ZrO_(2)/ZnZrO_(3) Luminescence material Light color adjustable phosphor Warm white emission W-WLEDs Rare earths

The diagnostic value of tenascin-C in acute aortic syndrome

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Journal of Geriatric Cardiology 2024年第3期21卷 359-368页

作者： ming ma Wei CHEN Hai-long CAO Jun PAN Qing ZHOU Xin-long TANG Dong-Jin WANG Department of Thoracic and Cardiovascular Surgery Nanjing Drum Tower Hospital Clinical College of Nanjing Medical UniversityNanjingChina Department of Thoracic and Cardiovascular Surgery Nanjing Drum Tower HospitalAffiliated Hospital of Medical SchoolNanjing UniversityNanjingChina Department of Thoracic surgery Kunshan Hospital of Traditional Chinese MedicineJiangsuChina

OBJECTIVES Misdiagnosis of acute aortic syndrome(AAS)significantly increases ***-C(TN-C)is an extracellular matrix glycoprotein related to cardiovascular *** elevation of TN-C in AAS and whether it can discriminate suddenonset of acute chest pain in Chinese remains *** We measured the plasma concentration of TN-C by ELISA in a cohort of 376 patients with chest or back *** to discriminate AAS from acute coronary syndrome(ACS)were compared and *** From October 2016 to September 2021,376 undiagnosed patients with chest or back pain were enrolled.166 of them were finally diagnosed as AAS,100 were ACS and 110 without cardiovascular diseases(NCV).TN-C was significantly elevated in AAS at 18.18 ng/mL(IQR:13.10–27.68)compared with 7.51 ng/mL(IQR:5.67–11.38)in ACS(Pmance of TN-C was superior to D-dimer and *** The concentration of serum TN-C in AAS patients was significantly higher than that in ACS patients and ***-C could be a new biomarker to distinguish AAS patients in the early stage after symptoms onset from other pain diseases.

关键词： acute cardiovascular elevated

Microstructure and thermophysical properties of Mg-2Zn-xCu alloys

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Transactions of Nonferrous Metals Society of China 2020年第7期30卷 1803-1815页

作者： Wan-peng ZHANG ming-long ma Jia-wei YUAN Guo-liang SHI Yong-jun LI Xing-gang LI Kui ZHANG State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co.Ltd.Beijing 100088China GRImaT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

The microstructure and thermophysical properties of Mg-2 Zn-x Cu alloys(x=0.5, 1.0 and 1.5, at.%) were investigated through microstructural and thermophysical characterization, heat treatment, and first-principles calculations. It was found that the addition of Cu had influence on the microstructure and thermophysical properties of the alloy. As the Cu content increased, the content of the MgCuZn phase increased in the as-cast alloys along with the electrical and thermal conductivities. After solution treatment, the eutectic structure partially decomposed and Zn atoms dissolved into the matrix, leading to the decrease in both the electrical and thermal conductivities of the alloy. During the early stages of the aging treatment, solute atoms precipitated from the matrix, thus increasing the electrical conductivity of the alloy. After aging for 24 h, the thermal conductivity of Mg-2 Zn-1.5 Cu alloy reached the maximum of 147.1 W/(m·K). The thermostable MgCuZn phases were responsible for increasing the electrical and thermal conductivities. Smaller amounts of Zn atoms dissolved in the matrix resulted in smaller lattice distortion and higher conductivities. The first-principles calculations findings also proved that the MgCuZn phases had very high conductance.

关键词： Mg-Zn-Cu alloy heat treatment electrical conductivity thermal conductivity first-principles calculations