稀土改性Fe-Al层表面Al2O3 薄膜的物相分布

在760 ℃下采用稀土改性包埋渗铝以及原位氧化方法制备Fe-Al/Al₂O₃复合涂层,研究了渗铝层和氧化膜的微观组织和相分布。结果表明,稀土改性渗铝层可分为3层：外层渗铝层、过渡层和内扩散层。渗铝层主要由FeAl相和Fe₃Al相组成。FeAl相主要集中在渗铝层的外层,为Al₂O₃氧化膜的选择性氧化提供了有利条件。氧化膜表面呈α-Al₂O₃脊状结构。此外,表面氧化铈的存在是由于氧化初期Ce向外扩散且与O₂的优先反应。氧化膜可分为2层,即纯α-Al₂O₃层和主要由α-Fe(Al)和Al、Fe、Ce的混合氧化物组成的过渡层。     

离子注入法在316L不锈钢基体上制备Al2O3 阻氚涂层

采用离子注入技术在316L不锈钢基体上制备了氧化铝阻氚涂层。对离子注入法的不同工艺参数对α-Al₂O₃涂层摩擦磨损、耐腐蚀、抗热震、阻氚性能的影响进行了研究。结果表明：温度、加速电压及离子注入剂量对α-Al₂O₃的含量均有影响。温度升高时, α-Al₂O₃的含量增加。增大加速电压及离子注入剂量时,α-Al₂O₃含量均出现先升高后降低的规律。离子注入剂量对涂层的摩擦磨损、耐腐蚀性能影响比较大：离子注入剂量越大,涂层的耐磨、耐腐蚀性能越好。涂层经过200次热震测试后未发生变化,抗热震性能较好。Al₂O₃膜层具有优异的阻氚性能,在600 ℃下能使316L不锈钢的氚渗透率降低3个数量级。     

粉末包埋渗铝与气氛渗铝对P92钢650℃饱和蒸汽氧化行为的影响

表面渗铝技术可以在不改变基体材料力学性能的基础上显著提高基体的抗高温蒸汽氧化性能。 利用低温粉末包埋和气氛渗铝两种方法在 P92 钢表面制备了铝化物涂层,并结合氧化增重法、扫描电镜观察及 XRD 分析,研究了两种工艺下铝化物涂层的 650 ℃饱和蒸汽氧化行为。 结果表明:P92 钢抗氧化能力不足,生成了由外层疏松层瘤状富铁氧化物与表面氧化膜下方内氧化物 FeCr₂O₄ 组成的双层结构氧化膜,外层富铁氧化膜在氧化 300 h 后发生剥落;低温包埋渗铝所得涂层为 β-FeAl 层,氧化 500 h 后试样表面形成极薄的保护性 α-Al₂O₃ 氧化膜(<0. 2 μm);气氛渗铝涂层为单层 Fe₃Al 结构,氧化 500 h 后试样外表面形成了 Fe₃O₄₊Fe₂O₃ 氧化膜,厚度为 1. 3 μm,靠近涂层表面生成单层连续 Al₂O₃ 氧化膜。 采用低温包埋和气氛渗铝均可提升 P92 钢的抗蒸汽氧化能力。     

双峰结构Mo-Si-B基体表面多层硅化物涂层的表征和抗氧化性能

由于在细晶Mo-Si-B合金中制备双峰分布的α-Mo晶粒能够在不显著降低合金强度的前提下大幅提高其断裂韧性,为了加强双峰结构合金的表面防护,同时保持其优异的力学性能,通过包埋渗在合金表面上制备了一个具有多层结构（MoSi₂,Mo₅Si₃和Mo₅SiB₂/MoB）的涂层。研究结果表明,相比在细晶结构基体上制备的涂层,双峰结构基体上的涂层表面较为粗糙,并且也表现出双峰分布的微观组织。此外,覆盖涂层后的双峰结构合金的断裂韧性依然良好,并且分布在涂层中的La₂O₃颗粒能够增韧涂层。具有涂层的双峰结构合金在1100~1300 ℃下展现出了卓越的抗氧化性,这是由于氧化过程中在涂层表面快速形成了一个薄且能自愈合的SiO₂-B₂O₃膜。随着氧化温度升高,SiO₂-B₂O₃膜的粘度降低,使得SiO₂-B₂O₃膜的厚度和氧化产物Mo₅Si₃均增加。并且,升高温度促进了Si和B的互扩散,加速了Mo₅Si₃和Mo₅SiB₂/MoB层的增长。在1300 ℃下,由于单峰结构的MoSi₂涂层拥有更多的晶界,使得含涂层的细晶合金相比含涂层的双峰结构合金表现出更多的氧化增重。     

激光重熔Al2O3-TiO2涂层的强韧性能

采用等离子喷涂和激光重熔复合工艺在Ti-6Al-4V基体上制备了Al₂O₃-TiO₂涂层,通过X射线衍射(XRD)、扫描电镜(SEM)、显微硬度试验和压痕试验等方法研究了激光重熔对涂层的组织及强韧性能的影响.结果表明,等离子喷涂Al₂O₃-TiO₂涂层中的主相为γ-Al₂O₃,而相应重熔涂层中的主相为α-Al₂O₃.激光重熔可消除喷涂态涂层内部的孔隙、微裂纹和层状堆垛等微观缺陷,获得致密化的组织,并使涂层与基体形成良好冶金结合.重熔涂层的硬度比相应喷涂态涂层约提高了50%,裂纹扩展抗力相比喷涂态涂层提高了近两倍.激光重熔纳米涂层中的未熔增强颗粒和纳米结构特性等对涂层起到了协同强化和韧化作用.     

从吸附角度观察Mg-Ca合金中Mg2Ca和 α-Mg的氧化：DFT研究

基于DFT计算O₂在α-Mg（0001）和Mg₂Ca（0001）上的吸附过程,以探明Mg-Ca合金中的α-Mg和Mg₂Ca氧化机理。结果表明,在吸附过程中,O₂与α-Mg和Mg₂Ca有很强的相互作用,且均为化学吸附,但Mg₂Ca的吸附结构不如α-Mg的吸附结构稳定。在氧化过程中,O₂与α-Mg和Mg₂Ca中的Ca和Mg原子发生反应,形成Mg-Ca-O氧化膜,从而提高Mg-Ca合金的抗氧化性。但Mg₂Ca的吸附结构稳定性比α-Mg差,因此Mg₂Ca形成的氧化膜对基体的保护作用比α-Mg弱。     

镍基高温合金Al-Si涂层1000℃抗高温氧化性能和退化机制研究

为研究Si对简单NiAl涂层抗高温氧化性能的影响规律,改变料浆中Si/(Si+Al)比值(8wt.%、17wt.%和30wt.%),制备了三种不同Si含量的改性NiAl涂层。采用XRD、SEM、EPMA等表征方法分析了简单NiAl涂层和三种Si改性NiAl涂层氧化前后的相结构和显微组织。结果表明：四种铝化物涂层主要相均为δ-Ni₂Al₃和β-NiAl相。Si以CrSi₂、Cr₅Si₃和Ni₂Si硅化物的形式存在于涂层表层。在1000℃氧化500h后,简单NiAl涂层具有最大的氧化增重为1.93mg.cm_-2^,而Si/(Si+Al)比值为8wt.%的Si改性NiAl涂层具有最小的氧化增重。在NiAl涂层中掺杂Si可促进α-Al₂O₃膜的形成,通过形成硅化物减少难熔金属元素向涂层表面扩散,改善氧化膜表面质量,降低氧化速率。但是掺杂过量的Si会降低涂层表层Al含量,使涂层在氧化后期出现β相不足的问题,无法维持表面Al的选择性氧化。因此,当料浆中Si/(Si+Al)为8 wt.%,涂层表面Si含量为9.6 at.%时,涂层具有最高的抗高温氧化性能。     

放电等离子烧结WMoNbTaV-Al2O3 高熵合金组织及磨损性能

以金属粉末为原料,采用放电等离子烧结技术制备新型含α-Al₂O₃的WMoNbTaV难熔高熵合金,研究了烧结温度对合金致密化行为、相结构、显微组织和耐磨性能的影响。结果表明：在1800~1900 ℃烧结时,WMoNbTaV-Al₂O₃高熵合金基体具有单一bcc相结构,Al₂O₃的平均晶粒尺寸为1.15 μm。随着烧结温度升高,合金的晶粒尺寸增大,致密度和显微硬度也在不断增高,在1900 ℃烧结时硬度达到7967.4 MPa。1900 ℃烧结得到的合金具有优异的耐磨性,磨损量仅为1800 ℃烧结合金的一半。且WMoNbTaV-Al₂O₃高熵合金的耐磨性远高于纯W材料。当磨料粒度为37.5 μm时,1900 ℃烧结的合金磨损量为0.9 mg,磨损性能是纯W材料的83倍。     

Ar/N2-Ar共溅射Ti掺杂对Ta2O5 涂层光学和力学性能的影响

为了探索Ar/N₂-Ar共溅射Ti掺杂对Ta₂O₅涂层光学性能和力学性能的影响,采用射频和直流磁控共溅射技术在玻璃基底表面制备了Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、原子力显微镜（AFM）表征了Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层的微观结构和表面形貌;通过紫外可见分光光度计测试了涂层的光学参数;采用纳米压痕仪测试了涂层的硬度和杨氏模量。XRD测试结果表明,Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层主要以Ta₂O₅为主体的非晶相结构组成。SEM和AFM结果显示,沉积在玻璃基底上的涂层未出现大面积空隙,溅射粒子在基底表面均匀堆积生长,并且涂层沉积厚度基本一致,厚度误差在5%以内。分别引入N₂和Ti及N₂-Ti共掺杂,均可降低Ta₂O₅涂层的粗糙度。光学测试结果表明,分别引入N₂和Ti元素,可以提高Ta₂O₅涂层的平均透射率至81%以上,而N₂-Ti共掺杂制备的N₂-Ti-Ta₂O₅涂层平均透射率降低。力学测试结果显示,与Ta₂O₅涂层对比,N₂-Ta₂O₅和N₂-Ti-Ta₂O₅涂层的硬度显著增大,Ti-Ta₂O₅涂层硬度基本一致。弹性指数（H/E）和塑性指数（H³/E²）表明,N₂-Ta₂O₅涂层和N₂-Ti-Ta₂O₅涂层具备更好的断裂韧性和抗塑性变形能力。在玻璃表面制备Ta₂O₅掺杂N₂和Ti元素的涂层,可以实现以N₂-Ta₂O₅涂层和N₂-Ti-Ta₂O₅涂层为代表的、同时具备优异光学性能和力学性能的多功能涂层。     

含氟化物银钎剂去除304不锈钢表面氧化膜的机理

使用银钎剂（由K₂B₄O₇、H₃BO₃、KF或KHF₂组成）去除304不锈钢表面氧化膜,研究了银钎剂对304不锈钢表面氧化膜的去除机理。结果表明,700 ℃时,在钎剂成分中某一成分的单独作用下,K₂B₄O₇和KF不能去除304不锈钢表面氧化膜;在任意2种成分的协同作用下,只有K₂B₄O₇与H₃BO₃的混合物在700 ℃下不能熔化,其余二元混合物均能与钢板表面氧化物反应;自由能（ΔG_m^θ）和反应平衡常数（K^θ）的计算结果显示,钎剂去除氧化膜的主要原因是该过程中钎剂中的F替代氧化物中的O,该反应的平衡常数达到 1.3×10¹⁶⁷,自由能小于零,反应可以进行。XRD结果显示,在2θ=18°位置的峰形发生改变,说明KF被KHF₂替代后,钎剂去除氧化膜的机理发生变化。含有KF和KHF₂的3号钎剂在540 ℃时可以有效去除钢板表面氧化膜,与钎剂的反应产物具有非晶结构特征。     

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).     

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.     

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.     

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。