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Microstructure and tensile properties of ultrafine grained copper processed by equal-channel angular pressing

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Rare Metals 2006年第6期25卷 697-703页

作者： WEI Wei CHEN Guang WANG Jingtao CHEN Guoliang Department of Materials Science and Engineering Jiangsu Polytechnic University Changzhou 213016 China Department of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China

Equal-channel angular pressing （ECAP） process was applied to a 12 mm ×12 mm ×80 mm billet of pure copper （99.98 wt.%） at room temperature. The shear deformation characteristics, microstructure evolution, and tensile properties were investigated. A combination of high strength （-420 MPa） and high elongation to failure （-25%） was achieved after eight ECAP passes at room temperature. The mixing of ultrafme grains （-0.2 μm） with nanocrystalline grains （-80 nm） resulted in high tensile strength and ductility.

关键词： equal-channel angular pressing copper microstructure tensile properties ultrafine grain size

Effects of multipass friction stir processing and Mg addition on the microstructure and tensile properties of Al 1050 alloys

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International Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 97-107页

作者： Shahin Arshadi Rastabi Masoud Mosallaee Department of Mining and Metallurgy Yazd UniversityYazdIran

The effects of multipass friction stir processing(FSP)and Mg powder addition on the different microstructure parts,including the stir zone(SZ),heat-affected zone(HAZ),and thermomechanically affected zone(TMAZ)of Al 1050 alloy were *** observations revealed that with the increase in the number of FSP passes,the grain size of the SZ decreased in the non-composite and composite samples,whereas that of the TMAZ and HAZ increased in the non-composite ***,the addition of Mg powder resulted in considerable grain refinement,and increasing the number of the FSP passes resulted in a more uniform distribution of Al-Mg intermetallic compounds in the in-situ composite *** of the tensile test showed that the non-composite sample that underwent four passes of FSP exhibited a higher elongation percentage and a ductile fracture in comparison with those of the base metal and the composite ***,this sample exhibited a brittle fracture and a higher tensile strength in comparison with the base metal and the non-composite *** fabrication of composite samples resulted in a remarkable enhancement in hardness in comparison with the base metal and the non-composite samples that underwent FSP.

关键词： friction stir processing Al alloy magnesium tensile properties hardness

Distribution of Phosphorus and Its Effects on Precipitation Behaviors and tensile properties of IN718C Cast Superalloy

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Acta Metallurgica Sinica(English Letters) 2019年第7期32卷 887-899页

作者： An-Wen Zhang Yan Yang Sha Zhang Dong Zhang Wei-Hong Zhang Da-Wei Han Feng Qi Yuan-Guo Tan Xin Xin Wen-Ru Sun Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China College of Material Science and Engineering University of Science and Technology of China. Shenyang 110016 China State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization Jinchang 737100 China

The effect of phosphorus on the precipitations of γ",γ’ and δ phases and associated tensile properties in IN718C alloy are investigated in this *** is revealed that P atoms are dissolved in the grain interior to a relatively high degree and hence influence the precipitation behaviors in the grain interior and improve the tensile strength of IN718C alloy.γ" and γ’ phases did not precipitate in the alloy without P addition during air cooling,while γ" and γ’ phases precipitated in the grain interior during air cooling in the alloys with P addition,and the amounts of γ" and γ’ phases increased with increasing P ***,the Vickers micro-hardness in the as-cast state increased gradually with increasing P *** double-aging state,the sizes of γ" and γ’ phases in the alloys with P addition were larger than that in the alloy without P addition,while the sizes were invariable when the P content(wt%)was higher than ***,the micro-hardness and tensile strength of IN718C alloy treated by double aging increased first and then kept invariable with increasing P *** precipitations of δ phases both in the grain interior and on grain boundaries were inhibited by P *** inhibitory effect of P on δ phase enhanced gradually with increasing content of P,but the plasticity increased first and then *** is more,the crack tended to propagate into the matrix around the particles(Laves phases and NbC carbides)in the alloys without P addition at the beginning of the tensile fracture,while it tended to propagate along the interfaces between the matrix and those particles in the alloys with P addition,which resulted from the synthetical effect of P on γ" γ’ and δ phases.

关键词： IN718C alloy Phosphorus γ" and γ’ phases δ phase tensile properties

Comprehensive tensile properties improved by deep cryogenic treatment prior to aging in friction-stir-welded 2198 Al-Li alloy

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Rare Metals 2024年第10期43卷 5403-5409页

作者： Jian-Qiu Sun Yue Ma Chong Gao Hong-Yun Luo School of Materials Science and Engineering Beihang UniversityBeijing 100191China Chinalco Research Institute of Science and Technology Beijing 100082China

In order to improve the comprehensive mechanical properties,deep cryogenic treatment(DCT)prior to aging was carried out on friction-stir-welded(FSW)2198 Al-Li alloy;afterward,the microstructure and tensile properties were characterized by means of optical microscopy(OM),transmission electron microscopy(TEM)and tensile *** results show that FSW 2198 alloy through DCT prior to aging(DAT)possesses superior tensile properties than conventional aging treatment(AT)The microstructural analysis reveals that DAT alloy exhibits a finer grain structure,since DCT might effectively alleviate the residual stress in FSW 2198 alloy and thus decrease the driving force for grain coarsening in subsequent aging ***,DCT generates dislocation multiplication,which provides more preferential nucleation sites for T1(Al_(2)CuLi)phase during subsequent aging treatment,resulting in high-density fine T1 phases and thin precipitate-free zone within DAT *** reasonable microstructure leads to DAT alloy possessing better strength-ductility combination compared to AT alloy.

关键词： Al-Li alloy Friction stir welding Deep cryogenic treatment tensile properties

Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy

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Journal of Materials Science & Technology 2018年第12期34卷 2256-2262页

作者： Wencai Liu Shi Feng Zhongquan Li Jiong Zhao Guohua Wu Xianfei Wang Lv Xiao Wenjiang Ding National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China

This study was conducted to discuss the effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5 Y（wt%） alloy, which was prepared by casting, and then homogenized and rolled at 200℃. The rolling process was conducted with 10% reduction per pass and five different accumulated strains, varying from 10% to 70%. The results indicate that the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloys are composed of α-Mg, β-Li, AlLi and Al;Y phases. After rolling process,anisotropic microstructure was observed. a-Mg phase got elongated in both rolling direction and transverse direction with the addition of rolling strain. Consequently, the strength of the alloy in both directions was notably improved whereas the elongation declined, mainly caused by strain hardening and dispersion strengthening. The tensile properties of the as-rolled alloys in the RD, no matter the YS, UTS or the elongation, are higher than those of the TD due to their larger deformation strain and significant anisotropy in the hcp α-Mg phase. In addition, the fracture and strengthening mechanism of the tested alloys were also investigated systematically.

关键词： Mg–8Li–3Al–2Zn–0.5Y Rolling Anisotropy tensile properties Strain hardening

Influence of Cold-Rolling Reduction on Microstructure and tensile properties of Nuclear FeCrAl Alloy with Low Cr and Nb Contents

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Acta Metallurgica Sinica(English Letters) 2022年第12期35卷 2101-2110页

作者： Hui Wang Biao Guo Xuguang An Yu Zhang Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610213China School of Materials Science and Engineering Xihua UniversityChengdu 610039China Interdisciplinary Materials Research Center Institute for Advanced StudyChengdu UniversityChengdu 610106China

FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding ***,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeCrAl alloys,with low Cr and Nb contents,is systematically *** the increase in CR reduction,the grain size of FeCrAl alloy is obviously refined after annealing because the increase in stored deformation energy leads to enhanced ***,the large CR reductions result in a severe mixed-grain microstructure,significantly reducing the uniform deformability of the FeCrAl *** dislocation density of the as-annealed FeCrAl alloy decreases with the increase in CR reduction,except for the excessive CR reduction of 50%.Moreover,the Laves phases are crushed and dissolved during CR and annealing,as well as large amounts of refined Laves phases are found after large CR *** pinning effect of the Laves phases can significantly improve the strength of FeCrAl ***,the strengthening mechanisms of FeCrAl alloy consist of fine-grain strengthening,dislocation strengthening and precipitation ***,the FeCrAl alloy,with a CR reduction of 30%,achieves optimal tensile *** study can provide theoretical guidance for the industrial production of the FeCrAl alloy.

关键词： FeCrAl alloy Cold-rolling reduction tensile properties Microstructure evolution Strengthening mechanism

Aging precipitation characteristics and tensile properties of Al-Zn-Mg-Cu alloys with different additional Zn contents

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Rare Metals 2021年第8期40卷 2160-2166页

作者： Kai Wen Bai-Qing Xiong Yong-An Zhang Xi-Wu Li Zhi-Hui Li Li-Zhen Yan Hong-Wei Yan Hong-Wei Liu State Key Laboratory of Nonferrous Metals and Processes GRIMAT Engineering Institute Co.LTD.Beijing101407China GRINM Group Co. LTD.Beijing100088China

The increase in zinc content in Al-Zn-Mg-Cu alloys provides an effective method to enhance the *** electron microscopy(TEM)and tensile test were employed to analyze the microstructure and tensile properties,respectively,of Al-9.3 Zn-2.0 Mg-1.8 Cu alloy(9.3 Zn alloy)and Al-9.8 Zn-2.0 Mg-1.8 Cu alloy(9.8 Zn alloy)with single-and double-stage aging *** results showed that the two alloys possessed a closed strength under single-stage peak-aging *** for double-stage aging treatment,9.8 Zn alloy had a higher strength values than 9.3 Zn alloy under the same aging *** the second step aging time prolonging,the strength gap was *** main precipitates for the two alloys with single-stage peak-aging state were GP zones andη’phase,while there were a majority ofη’phases andηphases for the two alloys under typical double-stage over-aging *** double-stage overaging state,the proportion of precipitate with large size for9.3 Zn alloy was larger than that for 9.8 Zn ***,a more obvious trend was revealed for the double-stage overaging *** gap of strength between the two alloys was explained by the difference of precipitation characteristics via interaction mechanism between precipitates and dislocations.

关键词： Zn content Al-Zn-Mg-Cu alloy Precipitation characteristics tensile properties

Improved tensile properties of Al_(0.5)CoCrFeNi high-entropy alloy by tailoring microstructures

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Rare Metals 2021年第9期40卷 2508-2513页

作者： Si-Zhe Niu Hong-Chao Kou Jun Wang Jin-Shan Li State Key Laboratory of Solidiﬁcation Processing Northwestern Polytechnical UniversityXi’an 710072China

The effect of heat treatment on microstructure and tensile properties of as-cast Al_(0.5)CoCrFeNi high-entropy alloy was investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM) equipped with energy-dispersive spectroscopy(EDS), and tensile *** results show that heat treatment strongly affects the microstructure, particularly the morphology of bcc phases,and improves tensile properties. Microstructure analysis reveals that rod-shaped and elliptoid phases appear in the matrix after heat treatment at 1150 ℃. Besides, under850 ℃ heat-treated condition, ultimate tensile strength increases by about 60% without sacrificing much plasticity,which can be attributed to the content of bcc phases and fine precipitates dispersed in the dendrites. For other heattreated conditions, tensile ductility increases by at least30%, especially 60% for heat treatment at 450 ℃, and strength also improves. Fracture analysis indicates that the fracture mode of heat treatment at 850 ℃ is a mixture of quasi-cleavage and ductile fracture, while the other heattreated conditions show the mode of ductile fracture.

关键词： High-entropy alloys Heat treatment Microstructure tensile properties

Strain rate sensitivity of tensile properties in high Nb containing TiAl alloys

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Journal of University of Science and Technology Beijing 2005年第6期12卷 535-539页

作者： Jianfeng Gao Xiangjun Xu Junpin Lin Xiping Song Yanli Wang Guoliang Chen State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.

关键词： TiAl alloys strain rate tensile properties thermal activation