粉末冶金银——氧化铜触头材料

采用粉末冶金工艺研制成Ａｇ－ＣｕＯ（１０）触头材料。结果表明：产品密度达９．６２～９．７ｇ／ｃｍ３，硬度ＨＢ７５０～８６０，电阻率２．２５～２．３９μΩｃｍ，抗弯强度３７０～４２０ＭＰａ；２００万次机械寿命和７周期交变湿热试验均能满足电力机车的使用要求。此外，在低压电器ＣＺ５接触器上可代替Ａｇ－ＣｄＯ（１５）触头     

碳化La2O3—Mo阴极材料的高温XPS研究

采用高温Ｘ射线光电子能谱（ＸＰＳ）对碳化Ｌａ２Ｏ３－Ｍｏ阴极材料表面Ｌａ的价成进行了研究。结果表明,材料中的Ｌａ２Ｏ３可以被Ｍｏ２Ｃ还原成单质Ｌａ。单质Ｌａ的结合能高于Ｌａ２Ｏ３的结合能。从实验上证实单质Ｌａ３ｄ５／２的结合能为８３５．９６ｅＶ,并首次给出单质Ｌａ３ｄ３／２结合能实验数值为８５２．２３ｅＶ。     

用单摆划痕法研究Al2O3f／Al—9Si合金在不同冲击速度下？…

为揭示ＭＭＣｓ材料的冲击磨损机理，采用单摆划痕法对Ａｌ２Ｏ３１／Ａｌ－９Ｓｉ合金耐冲击磨损行为进行了研究，结果表明：（１）在３ｍ／ｓ冲击速度下，随着增强相的体积分数增多，Ａ２Ｏ３１／Ａｌ－９Ｓｉ合金抗冲击磨损性降低。在４ｍ／ｓ冲击速度下，对同一种Ａｌ２Ｏ３１／Ａｌ－９Ｓｉ合金材料，冲击速度为４ｍ／ｓ时的耐冲击磨损性优于速度为３ｍ／ｓ时的耐冲击磨损性。９２）在冲击磨损过程中，Ａdisplay status     

反应层厚度对AI203／AgCuTi／Ti—6AI—4V接头强度的影响

通过保持一定钎焊温度,改变钎焊时间得到不同反应层厚度的ＡＩ２Ｏ３／ＡｇＣｕＴｉ界面。结合扫描电镜（ＳＥＭ）和力学试验结果,分析了反应层厚度对ＡＩ２Ｏ３／ＡｇＣｕＴｉ／Ｔｉ－６ＡＩ－４Ｖ接头强度的影响。结果表明：厚度为１．５μｍ时,接头强度达到最大值１２５ＭＰａ;厚度小于１μｍ,剪切试样沿反应层和ＡＩ２Ｏ３陶瓷界面断裂;大于３μｍ,沿反应层断裂,反应层厚度较薄时,接头强度取决盱界面强度和残余应力的大小;反应层厚度较厚时,接头强度取决于反应层自身强度和残余应力的大小。     

高强度、高电导率双相Cu-Ag合金

运用加工和热处理方法使Ｃｕ－Ｎｂ合金和Ｃｕ－Ａｇ合金具有均匀细微的双相纤维组织,其电导率高达８０％ＩＡＣＳ（ρ＝２．１５μΩ．ｃｍ）强度高达１ＧＰａ以上,文中介绍了ＭＭＳｃ双相Ｃｕ合金的组织特征及变形程度,热处理制度对Ｃｕ－Ｎｂ合金和Ｃｕ－Ａｇ合金的纤维组织,电导率,强度的影响。     

贵金属光学金相图谱之九

Ｐｄ－４２Ｉｒ合金（４０×）腐蚀剂ＨＮＯ３,铸态,粗大均匀的等轴晶。ｂ．Ａｇ－Ｃｕ－Ｓｉ合金（１２０×）腐蚀剂ＮＨ３＋少量Ｈ２Ｏ２,铸态,经５５０℃／２５ｄ处理,树枝晶。ｃ．Ａｕ－１６Ｎｉ－１０Ｐｄ合金（６４×）腐蚀剂ＣＨ１＋ＨＮＯ３＋Ｈ２Ｏ,在ＮＨ...     

内氧化粉体制备的Ag-SnO2接点材料的显微结构

Ａｇ－Ｓｎ－Ｍ（Ｍ＝Ｂｉ、Ｃｕ）合金粉末内氧化后经压制、烧结、挤压、加工制备成Ａｇ－ＳｎＯ２接点材料,用光学显微镜,Ｘ射线衍射和ＳＥＭ研究其显微结构,结果表明：在Ａｇ－ＳｎＯ２材料中存在Ａｇ,ＳｎＯ２、Ｂｉ２ＳｎＯ７和ＣｕＯ,氧化物以极细小的颗粒分布在银基体中。     

Ni－La_2O_3复合镀层中的质点弥散与组态研究

用金相、电子探针（ＥＰＭＡ）、透射电镜（ＴＥＭ）及高分辨电子显微镜（ＨＲＥＭ）对Ｎｉ－Ｌａ２Ｏ３复合电镀层的表面形貌及ＬａＯ３质点在镀层中的存在情况进行了研究．发现随着镀液中Ｌａ２Ｏ３颗粒含量增加，复合镀层中Ｌａ２Ｏ３的弥散量增多，镀层晶粒细化．Ｌａ２Ｏ３质点以两种组织状态均匀分布于镍层中：其一为纳米级晶体（绝大多数＜５０ｎｍ）的弥散状态；另一种为微米级（～１μｍ）的“聚合体”状态，是由更微小的纳米晶体（～１０ｎｍ）所组成，由于Ｎｉ－Ｌａ２Ｏ３复合镀层用作扩散渗铝制备Ｌａ２Ｏ３氧化物改性的铝化物涂层的基底层，文中还就复合涂层的Ｌａ２Ｏ３质点弥散与组态对改性的铝化物涂层的显微结构及其氧化行为的影响作了进一步探讨．     

La_1－zRz（Fe_1－x－yCoxAly）_（13）金属间化合物磁熵变特性研究

本文对用Ｆｅ、Ａｌ替代Ｃｏ的Ｌａ（Ｆｅ（０．７３）－ｘＣｏｘＡｌ（０．２７））（１３）系和用Ｒ（Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｄｙ，Ｇｄ）替代Ｌａ的Ｌａ１－ｚＲｚ（Ｆｅ（０．７１）Ｃｏ（０．０２）Ａｌ（０．２７））（１３）系的结构、磁性及磁熵变特性进行了研究。实验发现，Ｌａ（Ｆｅ（０．７８）－ｘＣｏｘＡｌ（０．２７））（１３）系的晶体结构均保持ＬａＣｏ（１３）的立方结构，每３ｄ原子的饱和磁矩与其电子数ｎｄ的关系在富Ｃｏ侧符合刚性能带模型，而在富Ｆｅ侧则与该模型不符。当ｘ＝０．０２时该化合物的居里温度在室温并有较高的磁熵变△ＳＭ，在１．１１ＭＡ／ｍ（１．４Ｔ）磁场下的（△ＳＭ）ｍａｘ为１３ｋＪ／ｍ３·Ｋ。对于Ｌａ１－ｚＲｚ（Ｆｅ（０．７１）Ｃｏ（０．０２）Ａｌ（０．２７））（１３）系，实验发现除Ｃｅ外，其它稀土元素均不能与Ｌａ、Ｆｅ、Ｃｏ、Ａｌ形成１：１３相，而是形成了２：１７相。     

Thermodynamic analysis of combusion synthesis and reaction hot pressing of Al2O3/B4C composite

１－ＩｎｔｒｏｄｕｃｔｉｏｎＢｏｒｏｎｃａｒｂｉｄｅｒｅｉｎｆｏｒｃｅｄａｌｕｍｉｎａｃｏｍｐｏｓｉｔｅｓ（Ａｌ２Ｏ３／Ｂ４Ｃ）ｈａｖｅｉｍｐｒｏｖｅｄｆｌｅｘｕｒａｌｓｔｒｅｎｇｔｈａｎｄｆｒａｃｔｕｒｅｔｏｕｇｈｎｅｓｓｏｖｅｒｔｈｅａｌｕｍｉｎａｃｅｒａｍｉｃ［１］．Ｍｏｒｅｏｖｅｒ,ｓｉｎｃｅｂｏｔｈｂｏｒｏｎｃａｒｂｉｄｅａｎｄａｌｕｍｉｎａｈａｖｅｌｏｗｄｅｎｓｉｔｉｅｓ（２．５１ａｎｄ３．９８ｇ／ｃｍ３,ｒｅｓｐｅｃｔｉｖｅｌｙ）,ｔｈｅｒｅｓｕｌｔｉｎｇｃｏｍｐｏｓｉｔｅ…     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would 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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.