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61.
A commercial AB5 hydrogen storage alloy was used as an additive to improve the electrochemical properties of Ml-Mg-Ni-based hydrogen storage alloys.The effect of AB5 alloy addition on the phase structure,charge/discharge characteristics,and electrochemical kinetics of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 alloy was investigated.The maximum discharge capacity of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 + 4 wt.% AB5 electrode reaches 406 mAh/g.The anodic polarization,cyclic voltammetry,and potential step discharge experiments show that the electrochemical kinetics of the electrode with additives was promoted,with the LaNi5 phase of AB5 alloy acting as electro-catalytic sites in the electrode alloy.The high-rate dischargeability of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 + 4 wt.% AB5 alloy electrode at 1100 mA/g reaches 60.9%,which is 9.4% higher than that of Ml0.90Mg0.10Ni3.08Mn0.13Co0.63Al0.14 alloy electrode.The cycling stability of the electrode with 4 wt.% AB5 alloy has also been improved. 相似文献
62.
以29320调心滚子轴承外圈为研究对象,对Zr41Ti14Cu12.5Ni10Be22.5非晶合金的铸造成形进行实验研究.通过对充型和凝固过程的数值模拟,得到合金熔体在充型过程中的速度场和温度场,以及凝固过程中的温度场和温度梯度场.结果表明,当浇铸温度为1200℃时,能以大于临界冷速率的冷却速率获得外形完整的铸件.采用... 相似文献
63.
《Intermetallics》2000,8(8):855-867
Phase equilibria between the α(A3), α2 (D019), β(A2 or B2) and the γ(L10) phases in the Ti–Al base ternary systems were investigated over the temperature range 1000–1300°C. The tie lines and the phase boundaries were determined by electron probe microanalysis using multiphase alloys. It was established that almost all the elements except Zr tended to partition into the β phase rather than into the α, α2 or the γ phase, while Zr mostly partitioned into the γ phase. At 1000°C, in the equilibrium state between the α2 and the γ phases, V, Cr, Mo, Ta and W partitioned to the α2 phase rather than to the γ phase, whereas Mn, Fe, Co, Ni, Cu and Zr tended to concentrate into the γ phase. The partition coefficients for the alloying elements were only slightly dependent on their concentration. Based on these data, the relative stabilizing effects of alloying elements on the α, α2, β and γ phases are discussed. 相似文献
64.
《Intermetallics》2000,8(9-11):1257-1268
The solidification pathways and phase equilibria at 1100, 900 and 700°C in seven Nb-rich alloys of the Nb–Ti–Al system were examined. The as-cast microstructures revealed that all alloys had undergone β solidification, extending the range of the β phase field further into the ternary system than previously reported. Changes in the atomic site occupancy preferences with alloy composition were examined for the B2 ordered β0 phase through atom location by channeling-enhanced microanalysis (ALCHEMI). A β to δ massive-like transformation observed in cast material, was reproduced in continuously cooled homogenized samples. The formation of a new phase, θ, based on the I41/amd body centered tetragonal structure was observed below 1100°C. In addition, a metastable hP18 structure, produced through an ω-type transformation of the β0 phase, was also observed. 相似文献
65.
66.
采用金相显微镜、扫描电镜(SEM)、X射线能谱(EDS)、X射线衍射(XRD)、透射电镜(TEM)及布氏硬度实验研究了热处理制度对GH4199合金组织和硬度的影响。结果表明:在1080~1180℃进行固溶处理,合金硬度随着加热时间的延长逐渐下降,固溶温度越低,达到稳定硬度值所需的时间越长,且稳定硬度值也就越高;随着固溶温度的增加奥氏体晶粒逐渐长大,超过1120℃后晶粒明显粗化;在1120℃以下,固溶处理时间对晶粒大小几乎没有影响;合金组织中含有大量的碳化物,主要以M6C形式存在,也有少量的M23C6和MC。随着固溶温度的增加和时间的延长,在晶界呈链状不均匀分布的碳化物逐渐溶解、粗化。 相似文献
67.
The surface corrosion behavior of an AA2024-T3 aluminium alloy sheet after friction stir welding was investigated by using an “in-situ observation” method. SEM observations showed that the density and degree of the pitting corrosion in the shoulder active zone were slightly larger compared to the other regions on the top surface. The origins of the pitting corrosion were in the regions between the S phase particles and the adjacent aluminium base. The effect of Al-Cu-Fe-Mn-(Si) intermetallic compounds on the pitting corrosion was attributed to their high self-corrosion potential which induced the anodic dissolution of the surrounding aluminium matrix. 相似文献
68.
Haifeng Dong Dayong Cai Zhengzheng Zhao Zhiyong Wang Yuhui Wang Qingxiang Yang Bo Liao 《Journal of Materials Engineering and Performance》2010,19(2):151-154
The study aims to postulate a theoretical hypothesis for the finishing period of ferritic rolling technique of the low carbon steel. The static softening behavior during multistage hot deformation of a low carbon steel has been studied by double hot compression tests at 700-800 °C and strain rate of 1 s−1 using a Gleeble-3500 simulator. Interrupted deformation is conducted with interpass times varying from 1 to 100 s after achieving a true strain of 0.5 in the first stage. The results indicate that the flow stress value at the second deformation is lower than that at the first one, and the flow stress drops substantially. The static softening effects increase with the increase of deformation temperature, holding temperature, and interpass time. The value of the ferritic static softening activation energy is obtained, and the static softening kinetics is modeled by the Avrami equation. 相似文献
69.
《Synthetic Metals》2005,155(3):576-587
Mono-substituted acetylene monomers with a liquid crystalline (LC) group are polymerized using rhodium, iron or molybdenum complex catalysts. LC polyacetylene derivatives with number-averaged molecular weights of 4000–330000 were obtained in 5–92% yield. The LC behavior is examined by X-ray diffraction, differential scanning calorimetry, and polarizing optical microscopy. The polymers prepared using rhodium or iron catalyst are confirmed to assume a cis form and to undergo an irreversible isomerization to the trans form upon heating. Photo-responsive polyacetylene derivatives are successfully synthesized through the introduction of an azobenzene moiety as a mesogenic core into the side-chain, and these forms exhibit a reversible photochemical cis-to-trans isomerization of the azobenzene moiety. 相似文献
70.
轧辊用新型高速钢特征温度下碳化物的析出动力学 总被引:1,自引:0,他引:1
采用示差扫描量热仪(DSC)测量了轧辊用新型高速钢材料不同类型碳化物的析出温度,并采用场发射扫描电镜(FESEM)观察其典型形貌和测定其相结构.在各特征温度下,分别对轧辊用新型高速钢保温15、20、25和30 min后快冷,采用金相统计软件对碳化物的体积分数进行了统计.结果表明:轧辊用高速钢在1300℃的温度快冷后,保温25 min时MC相的体积分数有最大值;1220 ℃快冷后MC和M2C相的体积分数均在保温20 min时有最大值;1150℃快冷后MC的体积分数一直增加,M2C的体积分数在保温20 min时有最大值,25 min时有最小值,而M6C的体积分数先增加后减少,保温20 min时有最大值. 相似文献