铝热-离心法制备TiC／FeNiCr复合涂层的耐热性研究

采用铝热．离心工艺在碳钢钢管内表面制备了TiC／FeNiCr金属陶瓷涂层。借助XRD，DSC，FESEM和显微硬度仪等方法研究涂层材料经历不同加热时间后的组织及结构稳定性，并利用等离子烧蚀实验测量涂层的耐烧蚀性能。结果表明，涂层材料由口．FeNiCr，TiC，NiAl及Nj3Al4相组成，基体组织细小致密，无粗大枝晶，没有微裂纹；经加热处理后，基体α-FeNiCr中弥散分布的TiC相尺寸无明显变化，材料显微硬度略有降低：由室温加热到1300℃过程中，材料不会发生相变；TiC／FeNiCr涂层的线烧蚀率为4．53μm／s，抗烧蚀性能比45^＃碳钢提高了32％。     

铝热-离心法制备TiC/FeNiCr复合涂层的耐热性研究

采用铝热-离心工艺在碳钢钢管内表面制备了TiC/FeNiCr金属陶瓷涂层.借助XRD,DSC,FESEM和显微硬度仪等方法研究涂层材料经历不同加热时间后的组织及结构稳定性,并利用等离子烧蚀实验测量涂层的耐烧蚀性能.结果表明,涂层材料由α-FeNiCr,TiC,NiAl及Ni3Al4相组成,基体组织细小致密,无粗大枝晶,没有微裂纹;经加热处理后,基体α-FeNiCr中弥散分布的TiC相尺寸无明显变化,材料显微硬度略有降低;由室温加热到1300℃过程中,材料不会发生相变;TiC/FeNiCr涂层的线烧蚀率为4.53 μm/s,抗烧蚀性能比45#碳钢提高了32%.     

一种纳米改性金属陶瓷材料的研究

研究了一种以TiC为基,纳米TiC和WC为改性剂,另加入Ni、Mo、Fe为粘结相的金属陶瓷耐磨材料,对该材料的强度、硬度和磁性进行了检测,并与相同成分的未加改性剂的TiC粒径≥2.4μm粗颗粒金属陶瓷进行了性能对比试验。结果表明:改性剂起到了明显的优化作用,经纳米改性后的金属陶瓷,既提高了强度、密度,也提高了硬度。     

机械研磨诱导316L不锈钢表层组织的演变

选取具有中等层错能的316L不锈钢进行表面机械研磨处理(SMAT)，制备出纳米结构表层，用X射线衍射(XRD)和透射电镜(TEM)研究横截面组织的演变过程．晶粒细化机理如下：奥氏体粗晶内部通过位错湮灭和重组形成位错胞；应变量和应变速率的增加诱发了机械孪生，形成了片层状孪晶；孪晶内部通过位错的运动使显微组织逐渐由片层状向等轴状转变，且晶粒尺寸逐渐减小、取向差逐渐增大；最终形成等轴状、取向呈随机分布的纳米晶组织．同时，对层错能对微观变形方式和纳米化行为的影响进行了讨论。     

铝合金表面高能喷丸纳米化过程中析出相的返溶

利用HRTEM和TEM研究了Al-Zn-Mg合会高能喷丸表面纳米化过程中微观结构的演变。结果表明，经表面高能喷丸处理，样品表面形成了厚度约20μm的纳米晶层，随温度的增加，平均晶粒尺寸由约20nm逐渐增加到约100nm；随着塑性变形量的增加，η相在纳米晶区内几乎完全返溶，形成晶粒尺寸小于100nm的单相α过饱和固溶体。其原因可能是由于α固溶体的晶粒尺寸超细化而导致固溶度增加。     

原始粉末粒度对Ti(C,N)基金属陶瓷组织性能的影响

采用粉末冶金方法制得四组不同粒度组合的Co-WC-Ti(C,N)金属陶瓷材料。对其室温力学性能进行测量,并采用XRD,SEM,EDX等方法对材料的相结构,显微组织等进行分析。研究表明,主要硬质相粒度的改变使相结构出现了一定程度的变化;以亚微米TiC为原始粉末细化了金属陶瓷组织中的晶粒;以纳米TiN为原始粉末使得晶粒大小趋向一致,分布均匀,并在一定程度上细化了晶粒;当TiC、TiN原始粉末分别为亚微米、纳米尺寸时,材料的综合力学性能最好。     

表面机械研磨诱导AISI 304不锈钢表层纳米化Ⅱ.晶粒细化机理

采用表面机械研磨处理(SMAT)在AISI 304不锈钢上制备出纳米结构表层，用透射电镜(TEM)研究组织演变过程．晶粒细化机理可归纳如下：位错在{111}面上滑移并相互交割形成网格结构；单系孪晶形成并逐渐过渡到多系孪晶；多系孪晶相互交割使晶粒尺寸不断减小，并在孪晶交叉处形成了马氏体相；孪晶系增多与孪晶重复交割强度加大使得细化晶粒的尺寸进一步减小；最终在大应变量、高应变速率和多方向重复载荷的作用下，形成等轴状、取向呈随机分布的马氏体相纳米晶组织．     

SHS-PHIP法制备TiC-Ni(Mo)金属陶瓷

采用Ti粉、碳黑、Ni粉和Mo粉的混合物，通过自蔓延高温合成(SHS)结合准等静压(PHIP)方法制备了TiC—Ni(Mo)金属陶瓷材料。X射线衍射结果表明，材料由TiC相和Ni合金粘结相组成。扫描电镜观察，球形的TiC颗粒较均匀地分布在Ni合金粘结相中,TiC颗粒尺寸约为2～4μm，在局部较大的TiC颗粒之间存在微孔缺陷。SHS—PHIP法制备的TiC—Ni(Mo)金属陶瓷材料具有良好的致密性和优良的力学性能。     

Ti(C,N)基纳米复合金属陶瓷材料的力学性能与微观结构

采用真空热压工艺制备了添加纳米ZrO2和微米WC的Ti(C,N)基纳米复合金属陶瓷材料,并研究了材料的力学性能与微观结构。结果表明:在纳米ZrO2添加量为5%、微米WC添加量为9.6%(质量分数,下同)时,Ti(C,N)基纳米复合金属陶瓷材料的综合力学性能较好,抗弯强度为1014MPa,断裂韧性为7.25MPa·m1/2,硬度为15.57GPa,其抗弯强度和断裂韧性比未添加纳米ZrO2与微米WC的Ti(C,N)基金属陶瓷材料分别提高了3.5%和18.1%。材料断裂模式为以穿晶断裂为主的穿晶/沿晶断裂混合模式。"晶内型"纳米结构弥散增韧、纳米ZrO2相变增韧以及裂纹桥联、裂纹偏转是其主要的增韧补强机理。     

金属陶瓷材料及其在切削刀具上的应用

文章论述了TiC基、Ti(C，N)基金属陶瓷的性能及其特点；作为刀具材料，金属陶瓷比硬质合金具有更多的优异性能，说明金属陶瓷作为刀具材料应用的范围。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.