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Structure and Thermal Parameters of Ni_(20)Pd_(80) Alloy

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Journal of Materials Science & Technology 2009年第2期25卷 208-210页

作者： S. Ahmad A.b. ziya A. Aziz z.I. zafar Department of Physics Bahauddin Zakariya University Department of Chemistry Bahauddin Zakariya University

The structure and thermal parameters of Ni20Pd80 alloy were studied by X-ray diffraction（XRD）. The diffraction experiments performed in the temperature range of 308-1100 K revealed that the alloy formed a face centered cubic （fcc） Al-type structure. The temperature dependence of the lattice parameters was investigated by using the bragg line displacement method showing that the lattice parameter increases with the increase of temperature. The mean linear thermal expansion （MLTE（%））, coefficient of thermal expansion （CTE, α）, the characteristic Debye temperature （（θD） and mean square amplitudes of vibration were determined from XRD data. The value of Debye temperature was found to be 253 K. It was found that temperature factor was independent of the static displacements.

关键词： Alloys Structure Thermal parameters X-ray diffraction (XRD)

THEORETICAL ANALYSIS FOR THE MOTION AND TEMPERATURE OF MELT DROPLETS IN SPRAY DEGASSING PROCESS

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Acta Metallurgica Sinica(English Letters) 2007年第3期20卷 193-198页

作者： R.z. Wu z.K. Qu b.D. Sun D. Shu J. Wang College of Materials Science ＆ Chemical Engineering Harbin Engineering University Harbin 150001 China State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Shanghai 200030 China Department of Chemistry Harbin Normal University Harbin 150025 China

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process couM be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets wouM solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results,

关键词： spray degassing hydrogen removal aluminum melt motion temperature

Improving the strength and SCC resistance of an Al-5Mg-3zn alloy with low-angle grain boundary structure

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Journal of Materials Science & Technology 2023年第30期161卷 63-73页

作者： z.C.Tang W.Xu D.Y.zhao b.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The strength of traditional Al-Mg alloys is relatively low because it mainly relies on solid solution *** a third component to form precipitation can improve their strength,but it usually leads to high-stress corrosion cracking(SCC)sensitivity due to the formation of high-density precipitates at grain boundaries(Gbs).So far,it is still challenging to improve the strength of Al-Mg alloys without re-ducing SCC ***,a nanostructured Al-5Mg-3 zn alloy with a good yield strength of 336 MPa and good elongation was successfully *** dynamic plastic deformation and appropriate anneal-ing treatment,near-equiaxed nanograins were introduced in the nanostructured Al-5Mg-3 zn alloy with a high proportion(71%)of the low-angle grain *** statistical investigations show that the pre-cipitation of active T’phase at Gbs has been greatly suppressed in the nanostructured Al-5Mg-3 zn alloy at sensitized conditions,and the area fraction of Gb precipitates is reduced from 72%to 21%,which sig-nificantly decreases the SCC *** study provides guidance for developing advanced Al-Mg alloy with high SCC resistance.

关键词： Al-5Mg-3 zn alloy Stress corrosion cracking Low angle grain boundary Nanostructured Dynamic plastic deformation

Evaluating instrumented Charpy impact strain signals using curve fitting equations

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维普期刊数据库

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Journal of Central South University 2014年第2期21卷 600-609页

作者： M.b.Ali S.Abdullah M.z.Nuawi A.K.Ariffin z.M.Nopiah Department of Mechanical and Materials Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia Department of Structure and Material Faculty of Mechanical EngineeringUniversiti Teknikal Malaysia Melaka

An effective and simple way to develop equations from impact strain signals was *** research has been performed in this area,but this equation is very important for evaluating input signals in finite element analysis impact tests and for obtaining additional information on material deformation and fracture processes under impact *** this purpose,dynamic impact responses were examined through signals obtained from a strain gauge installed on an impact striker connected to a data acquisition *** 6061-T6 was used to extract strain responses on the striker during Charpy impact *** analysis was performed using the I-kaz method,and curve fitting equations based on the equation for vibration response under a non-periodic force were used to evaluate the Charpy impact *** I-kaz coefficients and curve fitting equations were then compared and discussed with related parameters,such as velocities and *** and thickness were found to be related to the strain signal patterns,curve fitting equations and I-kaz *** equations developed using this method had R2 values greater than 97.7%.Finally,the constructed equations were determined to be suitable for evaluating Charpy impact strain signal patterns and obtaining additional information on fracture processes under impact loading.

关键词： charpy impact curve fitting I-kaz signal and strain

Comparing hydrogen embrittlement behaviors of two press hardening steels:2 GPa vs.1.5 GPa grade

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Journal of Materials Science & Technology 2022年第29期124卷 109-115页

作者： z.H.Cao b.N.zhang M.X.Huang Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina

*** The pursuit of advanced high-strength steels(AHSS)has been rising for the automobile industry to build lightweight and fuelefficient vehicles without compromising crashworthiness[1,2].The group of press hardening steels(PHS)is an excellent candidate that comprises high strength,high toughness,and good formability,which are optimal to build intrusion resistant components such as(ⅰ)A/b-pillar reinforcements,(ⅱ)bumper and door beams.

关键词： strength toughness steels

Logging and topographic effects on tree community structure and habitat associations in a tropical upland evergreen forest,Ghana

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Journal of Forestry Research 2021年第4期32卷 1361-1372页

作者： P.Addo-Fordjour E.K.boakye z.b.Rahmad Department of Theoretical and Applied biology College of ScienceKwame Nkrumah University of Science and TechnologyKumasiGhana School of biological Sciences Universiti Sains Malaysia11800 USM Pulau PinangMalaysia

We determined the response of tree community structure to logging disturbance and topography,and the patterns of tree-habitat associations in Tano Offin Forest Reserve,*** sampled trees in 27 20 m× 20 m plots randomly and equally distributed in three topographic habitats(slope,valley,and hilltop) in each of two forests:logged and *** topographic features,altitude and degree of slope,were measured and related with species ***,there were significant effects of logging and topographic habitat and their interaction on species diversity and composition,with the unlogged forest and valley habitat supporting higher *** diversity varied among the topographic habitats in the logged but not in the unlogged *** were topographic effects on abundance of individual species but not on tree community abundance and basal *** and its interaction with topographic habitat showed significant effects on tree abundance and basal *** species were associated with specific topographic habitats or a combination in the logged and unlogged ***,the patterns of habitat associations of the species differed between the logged and unlogged forests.

关键词： Altitude Community structure Disturbance Habitat heterogeneity Slope Topographic position

RESEARCH ON LASER DIRECT DEPOSITION PROCESS OF Ti-6Al-4V ALLOY

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Acta Metallurgica Sinica(English Letters) 2007年第3期20卷 171-180页

作者： S.Y. Gao Y.z. zhang L.K. Shi b.L. Du M.z. Xi H.z. Ji Mechanical Engineering College Yanshan University O~mhuangdao 066004 China beijing General Research Institute for Nonferrous Metals Beijing 100088 China

Laser direct deposition （LDD） of metallic components is an advanced technology of combining CAD/CAM （computer aided design/computer aided manufacturing）, high power laser, and rapid prototyping. This technology uses laser beam to melt the powders fed coaxiaUy into the molten pool by the laser beam to fabricate fuUy dense metallic components. The present article mainly studies the LDD of Ti-6Al-4V alloy, which can be used to fabricate aircraft components. The mechanical properties of the Ti-6Al-4V alloy, fabricated by LDD, are obtained using the tension test, and the oxygen content of used powders and deposited specimens are measured. In the present article, it can be seen that the mechanical properties obtained using this method are higher than the ones obtained by casting, and equal to those got by wrought anneal. One aircraft part has been made using the LDD process. because of this aircraft part, with sophisticated shape, the effect of the laser scanning track on the internal soundness of the deposited part was discussed.

关键词： laser direct deposition Ti-6Al-4V alloy mechanical property depositing process aircraft component

Ab initio molecular dynamics study on the local structures in Ce_(70)Al_(30) and La_(70)Al_(30) metallic glasses

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Chinese Physics b 2018年第5期27卷 405-411页

作者： F X Li J b Kong M z Li Department of Physics Beijing Key Laboratory of Opto-electronic Functional Materials ＆ Micro-nano Devices Renmin University of China Beijing 100872 China

Ab initio molecular dynamics simulations were performed to investigate the effect of similar elements on the shortto medium-range atomic packing features in Ce70Al30 and La70Al30 glass-forming alloys. 4 f electrons of Ce element in Ce70Al30 alloy were properly treated in electronic calculations. The local atomic structures in both alloys are qualitatively similar. However, the local environments of Al atoms in Ce70Al30 alloy show fluctuation with temperature in the cooling process, which could result from 4 f electrons of Ce elements. Surprisingly, the medium-range atomic packing features of Al atoms in both MGs are quite different, although Ce and La elements are similar. These findings are useful for understanding the enhanced glass-forming ability by similar element substitution in RE-based MGs from a medium-range structure perspective.

关键词： rare earth-based metallic glasses medium-range order molecular dynamics simulation

Examining the effect of the aging state on strength and plasticity of wrought aluminum alloys

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Journal of Materials Science & Technology 2022年第27期122卷 54-67页

作者： z.Qu z.J.zhang J.X.Yan P.zhang b.S.Gong S.L.Lu z.F.zhang T.G.Langdon Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Department of Mechanical Engineering University of SouthamptonSouthampton SO171BJUnited Kingdom

A general rule of strength and plasticity was proposed for three typical wrought Al alloys(2xxx,6xxx,and 7xxx)subjected to different aging *** of the work-hardening processes and dislocation configurations in tensile and compressive testing reveal that this general rule arises because there is a common mechanism for these three kinds of wrought alloys whereby the tendency for cross-slip increases monotonously with aging *** analyzing the strain hardening exponent and the stacking fault energy,it is demonstrated that the change in the dislocation slip mode is attributed mainly to the formation of second phases rather than to the matrix ***,a new work-hardening model was proposed for wrought Al alloys containing second phases and this explains the interaction between dislocations and second phases and other relevant experimental *** work is therefore beneficial for quantitatively investigating and optimizing the strength and plasticity of wrought aluminum alloys.

关键词： Wrought aluminum alloy Strength and plasticity Work hardening Dislocation slip mode Second phase