同基合金非磁控电弧离子镀镀层结构特征

对QA19-4/Cu及1Cr18Ni9Ti/45钢等两类同基合金的非磁控电弧离子镀镀层进行的扫描电镜分析结果表明,由于弧流携带的液滴较多,沉积层组织呈细密的片层状,层厚2-3μm.X射线衍射谱确认,这两类同基合金离子镀沉积分别由α（Cu）＋CuAl2＋CuAl及γ＋α组成,与焊接或铸态组织相当。两种镀层都有一定厚度的过渡层,从而使镀层-基材呈类冶金结合。施镀时间较长时,在沉积层增厚的同时,过渡层厚度也有所增长。这使得本项技术的实际应用领域可大大拓宽,不仅可进行厚层改性,而且可用于微磨损精密零件的修复。     

镍基激光熔覆合金对铝青铜耐腐蚀性能的影响

为增强铝青铜的抗腐蚀性能,通过激光熔覆技术在表面熔覆一层镍基合金熔覆层,通过静态腐蚀试验、电化学腐蚀试验、微观组织分析、扫描电镜等方法及腐蚀机理分析,对比QA19-4铝青铜和镍基合金熔覆层在10％H2SO4溶液中的腐蚀行为.研究结果表明:镍基合金熔覆层可大大提高QA19-4铝青铜的耐腐蚀性能.     

铜合金表面激光熔覆Fe铁基合金研究

采用激光熔覆技术在QA19-4铝青铜合金表面激光熔覆Fe基合金。采用OM、XRD、显微硬度计对熔覆层的组织、物相和硬度进行分析,测试了铝青铜基体、Fe基激光熔覆层的冲蚀磨损性能。结果表明:激光熔覆层与铝青铜基体形成了冶金结合,无孔洞、夹杂和裂纹等缺陷,熔覆层中主要组织为γ-(Fe-Ni)、CrFe_4、Cu_(3.8)Ni等。熔覆层显微硬度最高为498 HV,平均显微硬度320 HV,是基体硬度的2倍;随冲蚀时间的延长,熔覆层失重量比QA19-4铝青铜基体的失重量要低得多,熔覆层的耐磨性比基体组织的耐磨性提高了近2倍,激光熔覆层的冲蚀耐磨性能得到明显提高。     

Ni-P-B4C化学复合镀层的组织与性能

本文用扫描电镜、光镜及X光衍射仪对Ni-P-B4C化学复台镀屠的表面状态、内部组织结构进行了观察和分析，结果表明，随镀液中B4C粒子添加量的增加，镀层中B4C含量及镀层表面瘤状生成物也增加。复合镀层中B4C粒子均匀分布于Ni-P基体。B4C粒子的存在未改变Ni-P基体的物相组成及其变化。同时测定了复合镀层的力学性能，结果指出，随镀层中B4C含量增加，硬度提高，结合力下降，耐磨性显著提高。     

QAl9—2铝锰青铜衬套翻铆开裂原因分析

1 问题的提出我厂100件QA19-2青铜衬套在翻铆时有87件开裂。调查表明:当时衬套的机械加工、翻铆工艺、所用模具及操作人员(即外因)均无变动,我们着重对材料本身进行检查。 2 化学成分分析为防止混料我们对翻铆开裂的衬套作了化学成分分析,结果符合QA19-2青铜的化学成分规定。     

离子轰击镀对铀上铝镀层组织及防腐蚀性能的影响

研究了偏压镀、循环氩离子轰击镀和间歇式镀对铀上铝镀层组织及防腐蚀性能的影响．结果表明,3种离子轰击镀方法对铝镀层的组织产生强烈影响，且组织的致密程度与其防腐蚀性能呈现了较好的一致性．在-100V、-200V和-500V偏压条件下，镀层组织致密、防腐蚀性好；在-300V偏压下，镀层的致密性和防腐蚀性均差，未加偏压(0V)的次之；循环氩离子轰击镀和间歇式镀对提高镀层的致密性和防腐蚀性更为显著．离子轰击镀沉积的铝镀层均可不同程度地为铀提供好的保护效果．     

电沉积RE-Ni-W-P-SiC-PTFE非晶态复合材料的组织及结构

在碳钢表面进行了RE-Ni-W-P-SiC-PTFE(聚四氟乙烯)非晶态复合材料镀层的电沉积试验，研究了镀液的pH值、电流密度和热处理温度等因素对镀层的组织和相结构的影响，确定了电沉积工艺的最佳条件。结果表明，镀态镀层以非晶态的形态存在，随着热处理温度的升高，镀层逐渐向晶态转变，Ni3P相的衍射峰逐渐加强；在低于400℃时，镀层中含有PTFE相，在400％以上时，PTFE相已不存在，同时镀层中出现了W3O、NiO及(FeNi)相；500％时镀层已完全晶化，此时的物相组成与400％相近，只是W3O相被WO2代替。     

电泳-电沉积镍基纳米复合镀层Ni-Al2O3的耐蚀性能

采用电泳-直流电沉积和电泳-脉冲电沉积工艺制备了具有较高Al2O3含量的Ni-Al2O3纳米复合镀层,分析了纳米粒子对复合镀层表面形貌及微观组织的影响,并以静态浸泡试验法研究了镀层在质量分数为l0％的HCl溶液和l0％的H2SO4溶液中的耐蚀性能.结果表明,相比于纯金属镀层,电泳-电沉积纳米复合镀层的晶粒细小、组织致密...     

Na_2MoO_4添加量对Ni-Mo-P合金镀层微观组织及耐腐蚀性能的影响

采用化学镀技术在镁合金基体表面制备了Ni-Mo-P合金镀层,研究了Na_2MoO_4添加量对Ni-Mo-P镀层的微观组织、成分及耐蚀性的影响。利用扫描电镜观察了Ni-Mo-P镀层的表面和截面形貌,借助电化学工作站测试了Ni-Mo-P镀层在3.5wt%NaCl溶液中的极化曲线及阻抗谱。结果表明:Ni-Mo-P合金镀层表面形貌为胞状结构,当Na_2MoO_4添加量为0.5 g/L时,Ni-Mo-P合金镀层的胞状结构更细小,组织更紧密。0.5 g/L Na_2MoO_4添加量获得的Ni-Mo-P合金镀层的自腐蚀电位最正,为-0.8273 V,自腐蚀电流最小,为2.3041×10~(-6)A/cm~2,容抗弧半径达到最大,耐蚀性最佳。     

铝青铜热处理强化工艺试验研究

铝青铜具有较好的机械物理与化学性能，具有减磨性、无磁性、耐寒性、耐蚀性、冲击时不发生火花、无偏析倾向及良好的铸造、锻造，陛能。单相铝青铜合金具有高的塑性与韧性，其热挤压、锻压加工’陛能优良，但有较大的体积收缩率；双相铝青铜合金有较高硬度、耐磨性与强度，但塑性较低。铝青铜多用于制造航空工业齿轮，选用QA110-4-4或QA111-6—6制造，经优化热处理强化工艺处理后，     

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.     

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.