Ti-6242合金棒材偏析组织的分析和判定

采用便携式超声波探伤仪对Ti-662合金棒材进行探伤,对出现疑似偏析缺陷波的部位进行低倍组织观察,对确定的成分偏析区域再使用金相显微镜进行高倍组织观察,并使用显微硬度仪检测了正常区和偏析区的显微硬度,使用扫描电镜对正常区和偏析区进行SEM和EDS分析。结果表明,偏析区的硬度比正常区硬度偏高,偏析区Al、V、Sn元素含量正常,Cu和Fe元素含量较高,可以判定该偏析组织为由Cu和Fe元素引起的硬偏析,进而验证了超声波探伤可作为对Ti-662合金棒材偏析组织的判断方法。     

TC4钛合金棒材低倍组织亮斑分析

通过光学显微镜、维氏硬度仪、扫描电镜和EDS能谱分析对TC4钛合金棒材的两类异常低倍组织进行研究。结果表明:两类异常低倍组织中出现的白色亮斑缺陷不属于同一类型。第一类异常组织的亮斑区由单一α相组成,亮斑区的硬度显著低于正常区,属于成分偏析类的冶金缺陷;第二类异常组织的亮斑区为典型的X形貌,亮斑区的显微组织和硬度与正常区相差不大,属于热加工类缺陷。     

TC11合金大规格棒材异常组织分析

对TC11合金大规格棒材异常组织进行了分析。结果表明,异常组织为片状α和β相组成的编织状组织。与基体组织相比,该区域显微硬度高,微区成分Mo元素含量高、Al元素含量低。该异常组织是由于铸锭微区成分不均匀性在精锻过程中产生局部温升形成的β斑。     

钛合金棒材超声波探伤时底波后回波的缺陷定性分析

小规格钛合金棒材的超声波探伤中,成分偏析类缺陷的判定是一难点。在9.0 mmTC4钛合金磨光棒材的探伤中,发现一次底波与等边三角波之间存在游动回波,解剖分析属于合金成分偏析缺陷。TC4钛合金中合金元素贫化偏析区域与基体的声阻抗值相差很小,属透射类缺陷;同时这种缺陷使声波衰减,具有在一次底波信号之后出现游动回波的特点。并指出成分偏析缺陷可以大致分为两类：一种是与基体组织声阻抗相差较大的反射类缺陷;一种是与基体组织声阻抗相差很小的透射类缺陷。建议在小规格钛及钛合金棒材的超声波探伤中,关注一次底波与等边三角波之间的波形情况,避免漏检可能存在的透射类成分偏析缺陷。     

叶片用小规格TC4棒材的组织和织构研究

采用径锻加工方式制备叶片用Φ30 mm的小规格TC4合金棒材，并使用金相显微镜、XRD衍射仪及电子背散射(EBSD)技术研究棒材边部到心部的显微组织、物相组成和微观织构，并分析组织和织构对棒材力学性能一致性以及超声探伤杂波水平的影响。结果表明，径锻棒材内部晶粒得到充分细化，从边部到心部晶粒尺寸逐渐增大，径锻棒材的β转变片层组织被破碎。棒材中含有少量等轴状β相晶粒，分布在α_p的晶界和β转变组织中。棒材边部为■板织构，R/2和心部为■轴向的丝织构，且棒材的织构强度从边部到心部逐渐减弱。棒材抗拉和屈服强度的变异系数仅为0.24%和0.29%，具有优异的一致性。径锻加工小规格TC4棒材的超声波杂波水平为Φ0.8～9 d B，相对于轧制棒材杂波升高，这与径锻棒材显微组织不均匀区域的晶体取向变化有关。     

钛合金完全相变温度的检测方法

本文用金相试验淬火法测定了TC11、TC4、Ti-1023、Ti-679三种不同类型合金的β转变温度。试验结果表明,钛合金的完全相变温度取决于添加元素的化学成分和含量,成分偏析和组织不均匀对β转变温度的影响很小。     

新型钛合金TC8-1棒材显微组织及热处理工艺

针对适用于航空发动机压气机盘件而开发的TC8-1新型钛合金,分析锻制棒材的显微组织,测定β相变温度。合金适用双重退火热处理,根据组织中初生α相含量确定第一重退火温度,最终确定最佳热处理工艺参数。结果表明,TC8-1钛合金(α+β)/β相变温度约为1005 ℃,TC8-1锻制棒材为典型的双态组织,满足锻压要求;TC8-1合金最佳双重退火热处理工艺为：930 ℃×2 h,空冷+580 ℃×1h,空冷。     

可在400～500℃使用的TC4-B钛合金棒材研制

通过在TC4钛合金中添加Si、O、Mo、Zr、Sn合金元素,研制出名义化学成分为Ti-6Al-4V-0.3Si-0.3Mo-0.3Zr-0.3Sn-0.15O的TC4-B钛合金。并采用两种镦拔组合变形工艺,制备尺寸为?75 mm圆棒和51 mm×85.6 mm扁方棒。结果表明:经"三三一"工艺锻制的TC4-B钛合金棒材显微组织更为均匀;力学性能明显优于经常规工艺锻制的棒材,其室温拉伸强度可达1 000 MPa以上,500℃时拉伸强度可达636 MPa,伸长率为18%,断面收缩率为61%,可在400~500℃高温条件下使用。     

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 针对南钢部分合金结构钢棒材存在的硬度偏硬、影响锯切的问题，详细分析了硬度超标的影响因素，利用Gleeble热模拟试验研究了终轧温度对成品硬度的影响，采用合理调整钢材化学成分及电磁搅拌参数，控制自由氮含量，降低终轧温度，提高入坑温度等措施，将合金结构钢硬度降低到HB240以下，降低了碳成分偏析，碳质量分数极差由0.08%降低到0.04%，从而较大程度上改善了南钢合金结构钢切割加工性能。     

TbDyFe合金棒材的熔铸新工艺

在超高温度梯度定向凝固装置中研究了稀土超磁致伸缩材料TbDyFe合金棒材的制备工艺，用该工艺制备出了外观圆整，化学成分均匀的TbDyFe合金棒材；与电弧炉熔炼制备工艺相比，该工艺设备投资少，一套装置可完成TbDyFe合金棒材的熔炼浇注和定向凝固全过程，操作简单，成分控制准确；通过化学成分分析发现，正常熔炼时稀土元素Tb和Dy的烧损率分别小于2％和3％，烧损率低。     

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.