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Investigations on Flanging of Aluminum Alloy Tube Under Pulsed Magnetic Force

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Journal of Iron and Steel Research International 2012年第S1期19卷 438-441页

作者： YU Hai-ping JIANG Hong-wei LI Chun-feng national key laboratory for precision hot processing of metals Harbin Institute of Technology

In this work,the magnetic pulse forming process was used to flange the AA 3003-O aluminum alloy tube to improve the flanging formability *** results show that there are critical discharge energy values for the flanging dies with varied slope *** mechanism of magnetic pulse flanging process is the bulging in contrast to the expanding of the quasi-static *** the flanging with 90 slope degree,the limited hoop strain at the outer fringe could be up to 0.54 without rapture,to which the limit of simple tension limit is improved by 85%in *** 180 degree flanging at tube end can be achieved by one time magnetic pulse forming.

关键词： magnetic pulse forming flanging forming limit aluminum alloy tube

Numerical and Experimental Investigation of Electromagnetic Free Bulging of AZ31 Magnesium Alloy Sheet

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Journal of Iron and Steel Research International 2012年第S1期19卷 451-454页

作者： XU Jun-rui YU Hai-ping LI Chun-feng national key laboratory for precision hot processing of metals Harbin Institute of Technology

The electromagnetic free bulging experiment and the coupled-field numerical simulation of the EMF process were carried out to determine the possibility to improve the formability of magnesium alloy AZ31 sheets(1 mm thick)at room *** data were examined using strain *** numerical simulation for the electromagnetic sheet free bulging is performed by means of ANSYS FEA *** with quasi-static FLD results,increase in the major and minor principal strains of approximately 87%and 39%were achieved,*** effects of various process parameters on electromagnetic bulging of AZ31 magnesium alloy sheets were evaluated. Three-dimensional(3D)FE model is established to predict the electromagnetic bulging of the *** simulation results agreed well with experimental observations.

关键词： Electromagnetic sheet forming AZ31 magnesium alloy formability numerical simulation

Crystallographic Texture Evolution of ■-Fe_4N and Its Influences on Tribological Property of Nitrided Steel

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Acta Metallurgica Sinica(English Letters) 2018年第4期31卷 371-379页

作者： Yi-Xue Wang Mu-Fu Yan Zhao-Bo Chen Cheng-Song Zhang Yuan You national key laboratory for precision hot processing of metals School of Materials Science and Engineering Harbin Institute of Technology School of Mechatronics Engineering Harbin Institute of Technology School of Materials science and Engineering Southwest Jiaotong University School of Materials science and Engineering Qiqihar University

The crystallographic texture of γ′-Fe4N in compound layer and its influences on the tribological properties of nitrided steel 38CrMoA1 are investigated in the *** preferred orientation of（200）γ′is produced by low-temperature nitriding in atmosphere with low nitrogen-hydrogen ratio and increases with the nitriding *** preferred orientation of（220）γ′appears after 72 h cyclic *** orientation relationships（0001）ε,/（101）α′,and[ll0]J/[111]γ′（Ill）γ′/（0001）α′ and[011]γ′//[1210]ε,（200）γ′//（l10）α′,and[011]γ′//[111]α′,as well as（1T03）J（220）γ′,and[0100]J/[110]γ′,are established by first-principles *** misfit of interatornic distance（δ）,determining the phase transition resistance,is ***,two reaction pathways during nitriding,and α′→γ′and α′→ε→γ′,are assumed,which determines the preferred orientations of γ′-*** of wear tests demonstrate that the specimen with preferred orientation of（200）γ′ exhibits lower frictional coefficient and lower wear rate in comparison with the specimen with（220）γ′ preferred orien-tation.（111）γ′ texture usually relates to the lower frictional coefficient but higher wear rate due to the main slip system parallel to the sliding ***,the（200）γ′ preferred orientation has a positive significance in improving the wear properties of steels.

关键词： Crystallographic orientation First-principles calculation Plasma nitriding Tribologicaiproperty

Combination of eddy current and heat treatment for crack healing and mechanical-property improvement in magnesium alloy tube

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Journal of Magnesium and Alloys 2021年第5期9卷 1788-1801页

作者： Wenchen Xu Chuan Yang Haiping Yu Xueze Jin Guojing Yang Debin Shan Bin Guo School of Materials science and Engineering&national key laboratory for precision hot processing of metals Harbin Institute of TechnologyHarbin 150001China Institute of Machinery Manufacturing technology China Academy of Engineering PhysicsMianyangSichuan621900China

The continuous eddy current pulse treatment(ECPT)combined with heat treatment was employed to heal the microcracks in spin formed Mg alloy tubes and improve their mechanical properties in this *** results show that all the microcracks in different tube specimens were almost healed after different continuous ECPT schemes up to 15 *** schemes with less cooling intervals exhibited better healing effect and increased the strength and elongation of Mg alloy tubes more *** aging treatment,the strength improvement of the specimens with ECPT was more remarkable than that of the specimens without ECPT,and the elongation decrease of the specimens with ECPT was less evident than that of specimens without ECPT due to the segregation of RE elements on the crack ***,after solution treatment,the strength reduction and ductility improvement of the specimens with ECPT were more pronounced than that of the specimens without ECPT owing to the notable decrease of dislocation density of the specimens with *** narrowed cracks induced by ECPT and the segregation of precipitates in the vicinity of microcrack surface during aging treatment contributed to the maximum strength in the as-spun specimens with ECPT followed by aging treatment.

关键词： Microcrack Healing Eddy current pulse treatment Heat treatment

Preparation and Microstructure Evaluation of Directionally Solidified Nd-Fe-B Ingots by Electromagnetic Cold Crucible

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Journal of Iron and Steel Research International 2012年第S1期19卷 237-242页

作者： DING Hong-sheng FENG Kui WANG Yong-zhe CHEN Rui-run GUO Jing-jie national key laboratory for precision hot processing of metals School of Materials Science and EngineeringHarbin Institute of Technology

In this paper Nd-Fe-B ingots with hyper-peritectic composition were prepared through continuous and directional solidification by a novel electromagnetic cold crucible approach.A group of experiments were carried out in order to investigate the effects of input power and withdrawal velocity on the microstructure and growth orientation of Nd-Fe-B *** was found that the peritectic Nd;Fe;B phase grows with a planar interface at lower withdrawal velocity and changed into the dendritic interface at higher withdrawal *** result was explained by the theory of constitutional *** the volume fraction of ferromagnetic T;phase was found to be increased first and then decreased with the increasing of withdrawal velocity during the growth process of the ingots.

关键词： electromagnetic cold crucible directional solidification Nd-Fe-B structure ferromagnetic phase

Effect of Double Oxide Film Defects on Mechanical Properties of As-Cast C95800 Alloy

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Acta Metallurgica Sinica(English Letters) 2017年第6期30卷 541-549页

作者： Xin-Yi Zhao Zhi-Liang Ning Fu-Yang Cao Shan-Guang Liu Yong-Jiang Huang Jing-Shun Liu Jian-Fei Sun School of Materials science and Engineering Harbin Institute of TechnologyHarbin 150001China national key laboratory for precision hot processing of metals Harbin Institute of TechnologyHarbin 150001China School of Materials science and Engineering Inner Mongolia University of TechnologyHohhot 010051China

The morphology of double oxide film defects and their influence on the tensile mechanical properties of a commercial Cu-Al （C95800） alloy were investigated in this study. Plane castings were produced with two types of pouting systems, and their tensile properties were measured and then analyzed by means of Weibull statistics method. The fracture surfaces of the tensile specimens were examined using scanning electron microscopy equipped with energy-dispersive spectroscopy. A large amount of double oxide film defects were observed on the tensile fractured specimens of the topfilled plane castings, and their chemical composition is identified to be Al2O3. Weibull statistics analyses showed that the double oxide film defects significantly reduce mechanical properties of the castings investigated. Furthermore, the ultimate tensile strength is more obviously deteriorated by double oxide film defects than elongation.

关键词： Double oxide film defects C95800 alloy Running system Weibull statistics analysis

Impact of hydrogen microalloying on the mechanical behavior of Zr-bearing metallic glasses: A molecular dynamics study

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Journal of Materials science & technology 2020年第10期42卷 198-206页

作者： Binbin Wang Liangshun Luo Fuyu Dong Liang Wang Hongying Wang Fuxin Wang Lei Luo Baoxian Su Yanqing Su Jingjie Guo Hengzhi Fu national key laboratory for precision hot processing of metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China School of Materials science and Engineering Shenyang University of TechnologyShenyang110870China AVIC Manufacturing technology Institute Beijing100024China

Comparative studies on Zr35Cu65and Zr65Cu35amorphous systems were performed using molecular dynamic simulations to explore whether their hydrogenated mechanical behavior depends on the content of hydride-forming *** both of them present an increased strength and ductility after hydrogen microalloying,we observe the improved mechanical behavior for Zr35Cu65is more pronounced than that for *** these two samples,the distribution of configurational potential energy and flexibility volume respectively follows a similar H-induced variation tendency;all of the hydrogenated alloys not just have more stable atoms with smaller flexibility volume,but possess a larger fraction of readily activated ***,the atomic-scale details,based on the local"gradient atomic packing structure"model,indicate minor additions of hydrogen can promote more"soft spots"along with more strengthened"backbones"in the low-Zr alloy than that in the high-Zr sample,which endows the former with much higher strength and deformability after hydrogen *** regard this finding as a further step forward to distilling the tell-tale metrics of the H-dependent mechanical behavior observed in Zr-based metallic glasses.

关键词： Metallic glasses Molecular dynamics Mechanical behavior Atomic structure Hydrogen

Promoted application potential of p-type Mg_(3)Sb_(1.5)Bi_(0.5)for thematched thermal expansion with its n-type counterpart

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Journal of Materiomics 2020年第4期6卷 729-735页

作者： Jinsuo Hu Fengkai Guo Muchun Guo Jianbo Zhu Chen Chen Qian Zhang Wei Cai Jiehe Sui national key laboratory for precision hot processing of metals Harbin Institute of TechnologyHarbin150001China Department of Materials science and Engineering Harbin Institute of TechnologyShenzhenGuangdong518055China

Recently,n-type Mg3Sb1.5Bi0.5-based thermoelectric materials have attracted considerable attention for their extraordinary thermoelectric ***,thermoelectric generators should be made of the same material system to avoid thermal mismatch in the practical *** this work,p-type Mg3Sb1.5Bi0.5 which has almost the same composition as the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01 was synthesized by ball milling and spark plasma sintering,and then Na was chosen as an acceptor dopant to optimize the carrier concentration and further improve the thermoelectric ***0.0075Mg2.9925Sb1.5Bi0.5 sample gets the highest ZT of~0.5 at 773 *** Na0.005Mg2.995Sb1.5Bi0.5 sample shows the highest average ZT of~0.29 in the temperature range of 300 e773 K and matched thermal expansion behavior with the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01,which is of great significance for practical *** the Joule and Thompson heat into account,a high theoretical conversion efficiency(η)of~9.5%was calculated for the thermoelectric module consists of the present p-type Na0.005Mg2.995Sb1.5Bi0.5 and the state-of-the-art n-type Mg3.2Sb1.5Bi0.49Te0.01Mn0.01 with the leg length of 2 mm,and cold and hot side temperature of 300 K and 773 K,respectively,which shows a good potential for the use of this class of materials in the midtemperature power generation applications.

关键词： Thermoelectric Zintl phase p-type Mg_(3)Sb_(1.5)Bi_(0.5) Thermal expansion behavior Theoretical conversion efficiency

Introduction of rare-earth element Sc in alloy design to modify wear features of dual-phase high-entropy alloy

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Rare metals 2024年第2期43卷 817-828页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung Chiu Shi-Ping Wu Jing-Jie Guo Guo national key laboratory for precision hot processing of metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China School of Metallurgy and Materials University of BirminghamBirminghamB152TTUK

Tailoring the alloy composition,which induces the hard secondary phase to increase hardness and strength to improve the wear features,is a feasible approach for developing wear-resistant metal ***,a group of(AlCoCrFeNi)_(100–x)Sc_(x)(x=0–2.0,at%)high-entropy alloys(HEAs)are designed and the phase compositions and wear behaviors are ***-doped HEA series contain the primary body-centered cubic(BCC)and eutectic phases,in which the eutectic phase is composed of the alternately grown BCC and Laves *** addition promotes the diffusion of Ni atoms from BCC phase to form the Sc-rich Laves phase at the grain *** hardness increases due to solid solution strengthening and second phase *** the second phase strengthening plays a more significant role relative to solid solution *** phase and the oxides caused by wear heating prevent the direct contact between friction pair and HEAs,thus inducing a decreased wear rate from 6.82×10^(−5) to 3.47×10^(−5)m^(3)·N^(−1)·m^(−1).Moreover,the wear mechanism changes from adhesive wear,abrasive wear and oxidative wear to abrasive wear and oxidative wear.

关键词： High entropy alloy(HEA) Laves phase Hardness Wear mechanism