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Microstructure and creep behaviour of Mg-12Gd-3Y-1Zn-0.4Zr alloy

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Journal of Rare Earths 2013年第2期31卷 186-191页

作者：朱秀荣王军徐永东王荣聂景江朱利萍 Ningbo branch of china ordnance academy

Microstructure and creep behaviour of Mg-12Gd-3Y-1Zn-0.4Zr alloy prepared by squeeze casting were investigated. Transmission electron microscope （TEM） observation revealed that a kind of lamellar-shaped morphologies 14h long-period stacking order structure （LPSO） and dense β＇-phase precipitates were formed by heat treatment. The alloy exhibited good creep resistance. It was shown that the creep-resistant performance kept stable because of the restriction of dense β＇-phase precipitates and LPSO phases to the movement of dislocations, and the formation of β-phase plates took responsibility for the softening of material during creep. Stress and temperature dependence of the steady-state creep rate were studied over stress range of 50-100 MPa and a temperature range of 250-300 oC, and a dislocation creep mechanism was proposed for the alloy.

关键词： magnesium alloy Mg-Gd-Y-Zn-Zr long period stacking ordered (LPSO) creep behaviour rare earths

Microstructure and mechanical properties of Mg-xY-1.5MM-0.4Zr alloys

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Journal of Rare Earths 2011年第5期29卷 454-459页

作者：王军朱秀荣王荣徐永东聂景江凌国平 Zhejiang University Ningbo branch of china ordnance academy

Age hardening,microstructure and mechanical properties of Mg-xY-1.5MM-0.4Zr （x=0,2,4,6 wt.%） alloys （MM represents Ce-based misch-metal） were investigated by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results showed that the formed precipitates being responsible for age hardening changed from fine hexagonal-shaped equilibrium Mg12MM phase to metastable β＇ phase with bco crystal structure when Y was added into Mg-1.5MM-0.4Zr alloy,and the volume fraction of precipitate phases also increased. With the increase of Y content in Mg-Y-1.5MM-0.4Zr alloys,it was found that the age hardening was enhanced,the grain sizes became finer and the tensile strength was improved. The cubic-shaped β-Mg24Y5 precipitate phases were observed at grain boundaries in Mg-6Y-1.5MM-0.4Zr alloy. It was suggested that the distribution of prismatic shaped β＇ phases and cubic shaped β-Mg24Y5 precipitate phases in Mg matrix might account for the remarkable enhancement of tensile strength of Mg-Y-MM-Zr alloy. It was shown that the Mg-6Y-1.5MM-0.4Zr alloy was with maximum tensile strength at aged-peak hardness,UTS of 280 MPa at room temperature and 223 MPa at 250 oC,respectively.

关键词： magnesium alloy Mg-Y-MM-Zr age hardening precipitate phases rare earths

Thermal and Mechanical Properties of Graphene-Titanium Composites Synthesized by Microwave Sintering

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 707-713页

作者： Wen-Zhi Yang Wei-Ming Huang Zhi-Feng Wang Fu-Jun Shang Wei Huang Bao-Yu Zhang Ningbo branch of china academy of ordnance science College of Mechanical Engineering and Mechanics Ningbo University

The x wt%graphene-Ti composites（x = 0,0.2,0.3 and 0.4） were obtained using the powder metallurgy *** X-ray diffraction results demonstrated that the peak intensity of graphene increased monotonically with increasing graphene ***,the number of grain boundary and interface between graphene and matrix increased as graphene increased,which led to a sharp rise of thermal *** thermal conductivity and specific heat capacity of composites initially decreased drastically with addition of graphene,but then increased with increasing graphene content from 0.2 to 0.4 wt%.This phenomenon was connected with the graphene content and the characteristics of Ti matrix（pores,grain boundary and interface between graphene and matrix）.The variation of the compressive strength of composites was attributed to the interaction effects of the average grain size of the Ti matrix（d_m） and the volume fraction（V_f） and aspect ratio（A） of graphene.

关键词： Graphene Metal-matrix composites Thermal properties Compressive strength

Improved bias proportional navigation with multiple constraints for guide ammunition

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Journal of Systems Engineering and Electronics 2017年第6期28卷 1193-1202页

作者： Wei Pang Xiaofang Xie Tao Sun Department of ordnance science and Technology Naval Aeronautical and Astronautical University Yantai 264001 China

According to the infrared guidance ammunition(GA)attacking non-maneuvering targets on the ground or sea level,an improved bias proportional navigation(IBPN) is put forward,which can meet the constraints of the impact angle and the angle of attack(AOA). The motion equations and the collision triangle for the GA and the target are established in the two-dimensional plane. In accordance with the collision triangle, the integral value of the bias term is solved and BPN is designed on the basis of the relative velocity. To ensure the new method can be solved, closedloop equation of the IBPN is deduced. Considering the limitation of the AOA and the seeker angle, a four-phase IBPN is improved by setting different phases of the bias term. At the same time, the guidance law will make the impact angle achieve the desired angle and the normal acceleration also converges to zero. The simulation results show that the improved guidance law can be applied to various flight tasks and has great potential for engineering applications.

关键词： improved proportional navigation impact angle bias term look angle normal acceleration

Mechanical properties,corrosion behavior and microstructure evolution of zinc and scandium co-strengthened 5xxx alloy

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Journal of Rare Earths 2023年第11期41卷 1819-1826,I0006页

作者： Yanlin Pan Yue Xu Di Zhang Jishan Zhang Guxin Zhou Yujing Lang china academy of ordnance science Ningbo branch Ningbo315103China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China

Nowadays,it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive *** address this,the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranular corrosion resistance were prepared through chill casting,and the effects of minor Sc on mechanical properties,corrosion behavior and microstructure evolution of Al-5.0Mg-3.0Zn alloys were systematically *** results show that the Sc containing alloy has high number density and small size of intragranular precipitates,combined with the solid solution strengthening of Sc and the Al_(3)(Sc_(1-x),Zr_(x))second phase strengthening,the strength of Al-5.0Mg-3.0Zn-0.1Sc alloy is obviously ***,the intergranular corrosion resistance of the Sc containing alloy is also improved due to the formation of a large number of low angle grain boundaries and the weakening of the continuity of precipitated phases along the grain boundaries.

关键词： Al-Mg-Zn Scandium Mechanical properties Intergranular corrosion Transmission electron microscopy(TEM) Rare earths

Effect of ageing treatment on microstructures,mechanical properties and corrosion behavior of Mg-Zn-RE-Zr alloy micro-alloyed with Ca and Sr

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china Foundry 2021年第2期18卷 131-140页

作者： Yu Fu Chen Liu Hai Hao Yong-dong Xu Xiu-rong Zhu Ningbo branch of china academy of ordnance science Ningbo 315103China School of Materials science and Engineering Dalian University of TechnologyDalian 116024China

Effects of ageing treatment on the microstructures,mechanical properties and corrosion behavior of the Mg-4.2Zn-1.7RE-0.8Zr-xCa-ySr[x=0,0.2(wt.%),y=0,0.1,0.2,0.4(wt.%)]alloys were *** showed that Ca or/and Sr additions promoted the precipitation hardening behavior of Mg-4.2Zn-1.7RE-0.8Zr alloy and shortened the time to reaching peak hardness from 13 h to 12 *** maximum hardness of 77.1±0.6 HV for the peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy was *** microstructures of peak-aged alloys mainly consist ofα-Mg phase,Mg_(51)Zn_(20) phase and ternary *** Zn-Zr phase is formed within theα-Mg matrix,and the Mg_(2)Ca phase is formed near T-phase due to the enrichment of Ca in front of the solid-liquid ***,fine short rod-shapedβ′1 phase is precipitated within theα-Mg matrix in the peak-aged *** peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy exhibits optimal mechanical properties with an ultimate tensile strength of 208 MPa,yield strength of 150 MPa and elongation of 3.5%,which is mainly attributed to precipitation *** addition,corrosion properties of experimental alloys in the 3.5wt.%NaCl solution were studied by the electrochemical tests,weight loss,hydrogen evolution measurement and corrosion morphology *** results suggest that peak-aged alloys show reduced corrosion rates compared with the as-cast alloys,and minor additions of Ca and/or Sr improve the corrosion resistance of the Mg-4.2Zn-1.7RE-0.8Zr *** peak-aged Mg-4.2Zn-1.7RE-0.8Zr-0.2Ca-0.2Sr alloy possesses the best corrosion resistance,which is mainly due to the continuous and compact barrier wall constructed by the homogeneous and continuous second phases.

关键词： magnesium alloys age-hardening microstructure mechanical properties corrosion resistance

Experimental Investigation on Microstructure and Segregation of Ultrahigh Strength Al-Zn-Mg-Cu-Zr-Sc-Ni Alloy during Homogenization

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稀有金属材料与工程 2009年第A03期38卷 83-87页

作者： Li Zhenliang Xie Jianxin Chen Wei Zhai Jing Ren Huiping Wang Yufeng University of science and Technology Beijing Beijing 100083 China Ningbo branch of china academy of ordnance science Ningbo 315103 China Inner Mongolia University of science and Technology Baotou 014010 China

Ultrahigh strength Al-12Zn-2.4Mg-1.1Cu-0.20Zr-0.30Sc-0.30Ni alloy billets were fabricated by spray deposition method(the Osprey process). The effect of homogenization treatment on the microstructures and tensile properties were investigated by OM, SEM and EDS. The results show that adding small amount of Sc and Zr can greatly refine the grain size of the billet, with the average grain size of 10 μm. Grain-boundary becomes coarser firstly and then thinner under different homogenizing condition and grain coarsening were observed. The solute elements content of Zn inside grains has a peak at 490 ℃ /2 h, and Cu element, which was solved into matrix, can enhance the matrix hardness obviously during homogenization. The suitable homogenizing treatment is 460～490 °C/2 h for the hot extrusion of the studied alloy; after the optimized solid solution and T6 aging, the highest ultimate tensile strength (UTS) is 858 MPa with a ductility of 4.8%.

关键词：喷射沉积方法晶粒合金热挤压

Spatio-temporal variation of subtidal macrobenthic fauna and the ecological assessment of Longkou Artificial Island construction in Bohai Sea, china

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Journal of Oceanology and Limnology 2020年第6期38卷 1811-1824页

作者： LI Xiaojing CHEN Linlin ZHOU Zhengquan LI Baoquan LIU Xin YANG Lufei LIU Bo SONG Bo yantai Institute of Coastal Zone Research Chinese Academy of SciencesYantai 264003China University of Chinese academy of sciences Beijing 100049China Center for Ocean Mega-science Chinese Academy of SciencesQingdao 266071China University of yantai Yantai 264003China

To evaluate the status and changes of macrobenthic communities related to the construction of the Longkou Artificial Island(LAI)in the Bohai Sea,china,four annual surveys were conducted from 2010 to *** changes on environmental variations and macrobenthic communities were observed in 2013 after the LAI construction a couple of years *** changing environment was primarily presented by lower values of pH,dissolved oxygen(DO),organic material(OM)percentage,and higher salinity,suspended particulate matter(SPM)concentration and oil *** main dominant species shifted from Polychaeta taxa in 2010 to Mollusca taxa in 2013 due to the changes of environmental *** apparent miniaturization tendency in body size of macrobenthic species was presented from 2010 to *** biodiversity indices increased yearly from 2010 to ***,inter-site homogenization was observed in both the community structure and health *** AZTI Marine Biotic Index(M-AMBI)analysis showed that the health status of stations changed depending on its original status and distance to the ***,no significant differences were found in the spatial distribution of either environmental variables or abundance,biomass and biodiversity of macrobenthic *** the results will provide a basis for the long-term ecological assessment of reclamation.

关键词： macrobenthic assemblages benthic health assessment M-AMBI index Longkou Artificial Island Bohai Sea

Comparative Study on Constitutive Models to Predict Flow Stress of Fe-Cr-Ni Preform Reinforced Al-Si-Cu-Ni-Mg Composite

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Journal of Wuhan University of Technology(Materials science) 2017年第3期32卷 666-676页

作者：周灵展 YANG Liming PENG Yinjiang FEI Liangjun ZHU Xiurong Faculty of Mechanical Engineering and Mechanics Ningbo University Ningbo 315211 China Ningbo branch of china ordnance academy Ningbo 315103 China

The isothermal compression tests were carried out on Gleeble-3500 thermal-mechanical simulation machine in a temperature range of 298-473 K and strain rate range of 0.001-10 s^-1. The experimental results show that the flow stress data are negatively correlated with temperature for temperature softening, and the strain rates sensitivity of this composite increases with elevating temperature. Based on the experimental data, Johnson-Cook, modified Johnson-Cook and Arrhenius constitutive models were established. The accuracy of these three constitutive models was analyzed and compared. The results show that the values predicted by Johnson-Cook model could not agree well with the experimental values. The prediction accuracy of Arrhenius model is higher than that of Johnson-Cook model but lower than that of the Modified Johnson-Cook model.

关键词： Fe-Cr-Ni porous preform composite isothermal compression constitutive model