稀土La对精铸Cu-Ni-Fe-Al合金组织和电解性能的影响

针对Cu-Ni-Fe合金惰性阳极在铝电解过程中高温氧化和耐腐蚀性能差等问题,采用真空熔炼法制备了Cu-Ni-Fe-8Al合金,同时制备了不同La含量的Cu-Ni-Fe-8Al-xLa(x=0,1,2,质量分数)合金,研究了Al、La的添加对Cu-Ni-Fe合金微观组织结构及电解腐蚀性能的影响。结果表明,添加Al元素后,合金在高温电解过程中形成铝酸盐,抑制了Cu的外扩散;添加稀土La提高了氧化膜层与基体的结合性,进一步降低阳极材料的腐蚀损耗,但过高的La添加在一定程度上加速了合金的腐蚀。因此,添加适量Al和微量稀土La的Cu-Ni-Fe-8Al-La合金有望成为惰性阳极铝电解用备选阳极材料。     

微量Ce对AZ91镁合金微观组织及耐蚀性的影响

用X射线衍射(xRD)、扫描电镜(SEM)、能谱分析(EDS)、析氢法、动电位极化及浸泡实验等手段研究了添加微量稀土元素Ce对AZ91镁合金微观组织及耐蚀性的影响,并从热力学角度分析了Ce对提高合金耐蚀性的影响机制.结果表明,稀土Ce细化了合金的微观组织,使β-Mg<17>Al<,12>相变得断续、弥散,成分分布更为均匀,生成了Al4Ce相及Mg-Al-Mn-Ce-Fe的金属间化合物;稀土Ce使合金在3.5%Nacl溶液中的自腐蚀电位升高,与Al、O生成了不连续的保护性氧化膜,提高了合金的耐腐蚀性能;添加0.5mass?时合金的耐蚀性最佳.     

镧对高碳合金工具钢的高温抗氧化行为的影响

在热分析仪上采用增重法对未添加稀土与添加了0.004%稀土镧的高碳合金工具钢进行高温氧化实验。利用扫描电镜、X射线衍射对样品表面氧化膜进行分析。结果表明:在1000、1100℃时,恒温氧化动力学均符合抛物线规律,氧化膜具有保护性,添加稀土镧的高碳合金工具钢的氧化激活能提高了,氧化速率常数降低了。此时稀土镧的加入细化了氧化膜的晶粒,增强了氧化膜与基体的粘附性,使氧化膜不易脱落。在1200℃时,氧化增重曲线近似于直线,含有稀土镧的高碳合金工具钢的氧化速率更快,不利于提高合金工具钢的抗氧化性,氧化膜的保护作用也丧失。稀土镧的添加不会改变实验钢氧化膜的物相组成。     

微量稀土La改性6063铝合金及其氧化着色膜的研究

制备了含稀土La的6063铝合金,进行了阳极氧化和电解着色,并研究了氧化着色膜的耐腐蚀性能。结果表明:6063铝合金中添加微量稀土La能有效细化合金的晶粒,这与结晶时形核率增加以及晶粒长大速率的降低有关。当加入微量稀土La时,由于细晶强化作用和Mg2Si弥散强化作用使得挤压时效后的合金抗拉强度、塑性及硬度增加。在6063铝合金中,添加0.2wt%La是较为优化的参考含量,该含量条件下,6063铝合金氧化着色膜的膜基结合力及硬度最高。微量稀土La加入到6063铝合金中提高了基体阴极极化能力,氧化膜厚度和致密性增加,提高了氧化着色膜在Cl-溶液中的耐蚀性。     

过共晶高硅铸造铝合金磷—稀土双重变质处理

采用正交实验方法研究了磷、混合稀土变质剂添加量和变质处理温度对Ａｌ－２２Ｓｉ－１．２Ｃｕ－０．９Ｍｇ－１．０Ｎｉ过共晶高硅铸造铝合金变质效果的影响。结果表明，磷、稀土的添加量和磷变质处理温度对合金的变质效果起决定作用；稀土添加量对合金室温抗拉强度无明显影响。但能显著提高共高温强度；合金变质处理的最佳工艺如下：磷添加量为０．１％，稀土添加量为０．６％，磷变质温度为８３０℃，稀土变质温度为８１０℃。     

过共晶高硅铸造铝合金磷－稀土双重变质处理

采用正交实验方法研究了磷、混合稀土变质剂添加量和变质处理温度对Ａｌ－２２Ｓｉ－２ｃｕ－０．９Ｍｇ－１．０Ｎｉ过共晶高硅铸造铝合金变质效果的影响。结果表明：磷、稀土的添加量和磷变质处理温度对合金的变质效果起决定作用；稀土添加量对合金室温抗拉强度无明显影响，但能显著提高其高温强度；合金变质处理的最佳工艺如下：磷添加量为０．１％，稀土添加量为０．６％，磷变质温度为８３０℃，稀土变质温度为８１０℃。     

离子注入Ce对Fe—23Cr—5Al合金上AI2O3膜生长应力的影响

利用双面氧化弯曲方法原位测量了Ｆｅ－２３Ｃｒ－５Ａｌ合金空气中氧化形成的ＡＩ２Ｏ３膜平均生长应力。ＡＩ２Ｏ３膜内存在压应力。９００℃下氧化２０ｈ,膜内应力从３．５降低到２ＧＰａ,１０００℃下氧化１０ｈ,膜内应力从０．８降低到０．４ＧＰａ,合金表面离子注入１×１０＾１７Ｃｅ＾＋／ｃｍ＾２,增大了ＡＩ２Ｏ３膜的生长应力,其原因是添加稀土促进膜的横向生长,离子注入Ｃｅ同时增大了合金的氧化速率,促进了ＡＩ     

550℃高温钛合金的性能

Ｔｉ－５Ａｌ－４Ｓｎ－２Ｚｒ－１Ｍｏ－０．２５Ｓｉ－１Ｎｄ（简称Ｔｉ－５５）高温钛合金是我国自行设计研制的一种新型耐热钛合金．该合金通过添加适量稀土元素Ｎｄ,细化了合金组织,提高了合金抗氧化能力。稀土元素在合金中的内氧化,使合金基体中的氧含量降低并促使基体中的锡原子向稀土氧化物转移,抑制了Ｔｉ３Ｘ相的析出。同时,稀土氧化形成的稀土氧化物颗粒作为合金形核的弥散质点及其稀土氧化物颗粒周围所形成的位错亚结构对合金起到强化作用,使Ｔｉ－５５合金在使用温度下具有满意的热强性和热稳定性的最佳匹配。 近年,我…     

NiCrBSi-RE粉末制备新工艺及其对喷熔层组织性能影响

利用水玻璃作粘接剂,采用粘接法向NiCrBSi自熔合金粉末中添加稀土,从稀土分布、喷熔工艺性以及对喷熔层组织和耐蚀性的影响等方面研究水玻璃的应用可行性。结果表明,利用水玻璃作粘接剂可以在很大程度上改善稀土在粉末中的分布以及粉末的喷熔工艺性,制成的复合粉末流动性好、稀土分布较为均匀。水玻璃在喷熔过程中以渣的形式浮出金属熔覆层,对喷熔层的组织和耐蚀性没有不利影响。影响喷熔层组织和性能的是稀土添加量,添加适量稀土的喷熔层夹杂少,耐蚀性获很大提高。在复合粉末的生产工艺过程中,选择适当的水玻璃粘度对于降低研磨强度、减少喷熔过程中形成的渣量至关重要,在实现稀土与合金粉末良好结合的前提下应尽量降低水玻璃的粘度。     

稀土氧化铈(CeO2)与铸态Cu-Ni-Si合金性能

在Cu—Ni—Si合金中加入稀土氧化铈（CeO2），研究稀土氧化铈（CeO2）量对铸态Cu—Ni—Si合金组织与性能的影响。结果表明：适量添加稀土氧化铈（CeO2）能显著细化铸态合金的晶粒，提高合金抗拉强度，对电导率则影响较小。在合金中添加0．06％稀土氧化铈的Cu—Ni—Si材料，铸态条件下的抗拉强度可达4uMPa，比未加稀土的合金材料的抗拉强度提高了40．7％。过量添加稀土，合金的晶粒尺寸并不能继续细化，却显著降低材料的抗拉强度。     

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.     

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。