低能Si离子注入对TiN硬质薄膜性能的影响

采用低能MEVVA离子源技术对由磁过滤阴极真空弧沉积的TiN硬质膜进行了Si离子注入.采用场发射扫描电子显微镜、纳米硬度测试等方法,研究了基体离子注入剂量对薄膜性能的影响.结果表明,Si离子注入能在薄膜表面形成均匀细小的纳米颗粒.使基体及薄膜硬度从33 GPa提高到56 GPa,弹性模量从360 GPa提高到750 GPa.对薄膜进行多(4)次注入,硬度和弹性模量的提高并不显著,但对基体离子注入充分,薄膜的整体硬度和吸收塑性变形能的能力均有显著提高.     

Cr-Ti-N系多层膜成分及周期对抗冲蚀性能的影响

苛刻环境下发动机组件存在严重的固体颗粒(SPE)冲蚀,导致其可靠性降低。为研究多层膜成分及调制周期对膜层冲蚀性能的影响,利用金属蒸发真空弧离子源(MEVVA)和磁过滤阴极真空弧复合离子束沉积技术在AM355基材表面制备交替周期分别为5、13和26的3组CrNx/TimCr1-mN、TiNy/TimCr1-mN多层膜。采用微粒喷浆冲蚀试验机、场发射扫描电子显微镜(FESEM)、X射线衍射仪(XRD)等对膜层冲蚀性能、形貌及物相结构进行测试表征。结果表明:采用该技术制备的CrNx/TimCr1-mN、TiNy/TimCr1-mN多层膜结构致密、交替层变化明显。随着交替周期的增加,两体系多层膜的晶面间距减小,抗冲蚀性能得到提高,分别提高了8倍和20倍以上。     

新型多弧磁过滤系统对TiAlN薄膜的组分调控

针对磁过滤阴极真空电弧沉积技术制备多元复合薄膜的不足,设计研制一种新型的多弧磁过滤系统。该多弧磁过滤系统由两个支线管和一个干线管组成“Y”型的三通管结构。通过有限元分析和试验测量确定该新型多弧磁过滤器的最佳运行参数为：支线管和干线管的长度分别为180和230 mm,内径为200 mm。支线管和干线管的磁场强度分别为40和90 mT。采用该新型多弧磁过滤系统制备TiAlN多元复合薄膜,结果表明：该新型多弧磁过滤系统可实现多元复合薄膜的组分调控,并且膜层的表面形貌光洁,膜层元素分布均匀。     

复合离子束制备氮化物多层膜的抗冲蚀性能

为了在TC4钛合金上获得抗冲蚀性能优良的膜层,利用金属蒸发真空多弧(Metal evaporation vacuum arc,MEVVA)离子源和阴极真空磁过滤弧复合离子束沉积技术在TC4钛合金基材表面制备Cr/Cr-N、Ti/Ti-N、Cr-Ti/Cr-Ti-N、Ti-Al/Ti-Al-N 4种体系的多层膜。采用努普显微硬度计、划痕仪、微粒喷浆冲蚀试验机、场发射扫描电子显微镜(FESEM)、体式显微镜等仪器对不同体系膜层的力学性能及形貌进行测试表征,对比研究各膜层体系抗冲蚀性能的机理。结果表明:该技术制备的膜层致密、交替层结构明显;不同膜层体系的抗冲蚀性能差异较大,尤以二元金属及其氮化物交替复合多层膜具有较好的抗冲蚀性能,其中CrTi/Cr-Ti-N体系的膜层抗冲蚀性能相比基体提高10.1倍以上,其次为Ti-Al/Ti-Al-N、Ti/Ti-N、Cr/Cr-N,分别提高6.1倍、4.1倍和2.3倍。     

离子注入对TC4钛合金TiN/Ti涂层结合力和抗砂尘冲蚀性能的影响

目的通过离子注入提高TiN/Ti涂层的结合力和抗冲蚀性能。方法先采用金属蒸气真空弧(MEVVA)离子源在TC4基体上分别注入四种离子(Mo、Ti、Nb、Co),再用磁过滤真空阴极弧(FCVA)技术制备TiN/Ti涂层。采用非球面测量仪、AFM、XRD和纳米压痕仪,对四种离子注入的TC4基体表面粗糙度、表面形貌、物相结构、纳米硬度和弹性模量进行表征,采用划痕仪测量涂层的结合力,采用涂层冲蚀考核平台对不同试样进行砂尘冲蚀性能试验。结果经过Mo、Ti、Nb离子注入的TiN/Ti涂层的结合力和抗冲蚀性能都有提高,其中Mo离子注入的TiN/Ti涂层的结合力达71 N、耐冲蚀时间为80 min,与未离子注入涂层相比,分别增加31.5%和77.8%,而平均冲蚀率降低39.5%,仅为0.0078mg/g。Co离子注入的TiN/Ti涂层的结合力仅为40 N,平均冲蚀率增大了19.0%,达0.0433 mg/g,其抗砂尘冲蚀性能明显下降。结论离子注入涂层的抗砂尘冲蚀性能与结合力密切相关,随着结合力的增大,TiN/Ti涂层的平均冲蚀率减小,其耐冲蚀时间增加,选择合适的离子注入可提高TiN/Ti涂层的抗冲蚀性能。     

磁过滤的阴极弧等离子体源及其薄膜制备

采用磁过滤弯管滤除阴极弧等离子体中的大颗粒,研究了偏压和导向磁场对磁过滤弯管传输效率的影响。建立了磁过滤弯管中正交电场和磁场下的等离子体扩散模型,分析各个参数对等离子体传输的作用规律。采用磁过滤的阴极弧等离子体源制备了NbN膜,研究了沉积温度对膜层特性的影响。     

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 利用磁过滤阴极电弧镀分别在硬质合金和高速钢基体上沉积厚度约2～3μm的TiN薄膜,并用MEVVA源离子注入装置对TiN薄膜注入金属离子V+和Nb+。应用北京同步辐射装置（BSRF）的同步辐射光源,采用掠入射X射线衍射（GIXRD）的方法对TiN薄膜表面离子注入层的微观结构进行了分析研究。结果表明：未经过离子注入的TiN薄膜均存在特定方向的择优取向,而较小剂量(1×10ˇ17ions/cm2)的离子注入可以使晶粒细化、择优取向减弱或改变;当离子注入的剂量达到5×10ˇ17ions/cm2时,TiN薄膜表面离子注入层被非晶化。结合透射电镜的研究结果,观察到TiN薄膜表面非晶层的厚度约为50～100nm,并简要地讨论了离子注入过程对微观结构的影响机制。     

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  利用磁过滤阴极电弧镀在硬质合金上沉积厚度约2~3 μm的TiAlN薄膜,并用MEVVA源离子对TiAlN薄膜注入金属离子V+和Nb+。应用北京同步辐射装置（BSRF）的同步辐射光源,采用掠入射X射线衍射（GIXRD）的方法对TiAlN薄膜表面离子注入层的微观结构进行分析研究。结果表明：未经过离子注入的TiAlN薄膜主要组成相是没有择优取向的Ti3AlN伴有少量AlN,而较小剂量(1×1017 ions/cm2)的离子注入都可以使Ti3AlN产生（111）上的择优取向和细化晶粒,且AlN消失;当离子注入的剂量达到5×1017 ions/cm2时,注入V+的Ti3AlN择优取向变为（210）,并产生TiN相;注入Nb+ 的各个衍射峰完全消失,说明TiAlN薄膜表面离子注入层被非晶化,结合透射电镜的研究结果,观察到非晶层的厚度约为80~100 nm。     

同步辐射掠入射X射线衍射法研究TiA1N薄膜离子注入层的微观结构

利用磁过滤阴极电弧镀在硬质合金上沉积厚度约2～3μm的TiA1N薄膜,并用MEVVA源离子对TiA1N薄膜注入金属离子V+和Nb+.应用北京同步辐射装置(BSRF)的同步辐射光源,采用掠入射X射线衍射(GIXRD)的方法对TiA1N薄膜表面离子注入层的微观结构进行分析研究.结果表明:未经过离子注入的TiA1N薄膜主要组成相是没有择优取向的Ti3AlN伴有少量A1N,而较小剂量(1×1017ions/cm2)的离子注入都可以使Ti3AlN产生(111)上的择优取向和细化晶粒,且A1N消失;当离子注入的剂量达到5×1017ions/cm2时,注入V+的Ti3AlN择优取向变为(210),并产生TiN相;注入Nb+的各个衍射峰完全消失,说明TiA1N薄膜表面离子注入层被非晶化,结合透射电镜的研究结果,观察到非晶层的厚度约为80～100 nm.     

TC4钛合金表面TiAlN/Ti涂层的抗冲蚀性能研究

目的 通过明晰TC4钛合金表面不同结构的TiAlN/Ti涂层的冲蚀机制,为提高TC4钛合金的抗冲蚀性能、制备具有良好冲蚀性能的涂层奠定基础.方法 采用磁过滤真空阴极弧(FCVA)与金属蒸汽真空弧(MEVVA)技术,按照一定方式在TC4钛合金表面制备相同厚度不同层数的TiAlN/Ti涂层,采用扫描电镜(SEM)、光学显微镜、纳米压痕仪,对TiAlN/Ti涂层的微观结构和力学性能进行表征和分析.采用冲蚀试验平台,通过参数的调整来模拟沙尘环境,开展TC4钛合金和TiAlN/Ti涂层的冲蚀试验,计算获得冲蚀率.采用Proto-LXRD应力仪测试分析冲蚀前后TiAlN/Ti涂层的残余应力,利用SEM对涂层的冲蚀形貌进行表征和分析,并探讨涂层冲蚀损伤机理.结果 相比于TC4基体试样,层数为4、8、12层的TiAlN/Ti涂层试件冲蚀后的质量损失分别降低了86.9％、91.3％和94.0％,残余压应力分别增加了34、135、203 MPa.对比冲蚀区表面形貌,当涂层的层数为4层时,冲蚀区涂层脱落明显;当涂层层数为8层时,冲蚀区涂层局部有脱落;当涂层层数为12层时,冲蚀区涂层脱落不明显,对基体的防护较好.结论 MEVVA离子源注入技术显著提高了涂层的致密度和涂层与基体间的结合力.TiAlN/Ti涂层能显著改善试样的表面性能.相同涂层厚度下TiAlN/Ti涂层的层数越多,H3/E2值越大,抗冲蚀性能越优异.     

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.