Zr-Sn-Nb新型锆合金板材加工过程中不均匀组织与织构演变

利用XRD,SEM-ECC,TEM和EBSD技术,研究了Zr-Sn-Nb系新型锆合金板材加工过程的微观组织及织构演变.结果表明,β相淬火得到的随机织构经热轧后形成沿横向倾斜的基面织构,随后的加工过程均保留该织构;热轧及两次冷轧后的基面织构都为〈1010〉方向平行于轧向(〈1010〉//RD),而退火后转变为〈1210〉方向平行于轧向(〈1210〉//RD).淬火形成的网状魏氏组织经热轧转变为不均匀形变组织,两次冷轧使组织的不均匀性更显著,最终退火得到完全再结晶组织;轧制形成的难变形晶粒多为晶粒C轴平行于轧板法向(C//ND)的取向;最终退火板材的大晶粒多为〈1210〉//RD的基面织构,小晶粒则以〈1010〉//RD为主.结合锆合金的变形及再结晶机制对轧制时产生的不均匀组织及再结晶过程的织构转变进行了分析.     

硅元素对钽丝再结晶行为的影响

采用显微硬度测量、取向分布函数 (ODF)分析及显微组织观察 ,研究了在不同退火温度以及掺硅与未掺硅条件下钽丝的再结晶行为。研究发现 :在 136 0℃退火时掺硅对钽丝的再结晶有阻碍作用 ,晶粒变细 ,丝织构主要由 { 110 }〈0 0 1〉组成 ;当退火温度升高至 15 0 0℃时 ,{ 12 0 }〈0 0 1〉再结晶织构消失 ,在未掺硅钽丝中发现了新的 { 4 41}〈110〉织构组分 ,与初次再结晶织构组分 { 12 0 }〈0 0 1〉之间存在一个近似于 84°〈110〉的转动关系 ,此时 ,掺入硅元素反而促进了再结晶的发展 ,晶粒变得粗大且不均匀。这种现象可以用硅化物的形成与溶解来解释。     

电场退火对工业纯锌板再结晶织构的影响

利用X射线衍射的三维取向分布函数,研究工业纯锌板在160℃时电场与非电场退火保温不同时间条件下的再结晶织构的形成与演变,同时进行显微硬度测试。结果表明：电场退火推迟轧制工业纯锌板再结晶进程,从而导致电场退火样品的显微硬度值均高于非电场退火样品的显微硬度值。电场显著提高退火后样品的再结晶织构强度,即电场明显促进冷轧{101 8}面织构向再结晶{101 3}〈101 1〉板织构的演变,而且这种影响在再结晶晶粒的长大阶段表现得尤为突出。电场并没有改变工业纯锌板退火过程中再结晶织构的形成机制。     

退火温度对Fe-Mn-TWIP钢微观结构的影响

通过光学显微镜、X射线衍射技术和EBSD技术研究了退火温度对Fe-Mn-TWIP钢的微观结构的影响,结果表明冷轧态TWIP钢完成退火再结晶后,组织为全部的奥氏体,随着退火温度的提高退火晶粒的尺寸增大,在1000 ℃时达到了30～50μm.织构分析表明,当退火温度低于700 ℃时,受冷轧织构的影响,晶粒取向变化较小;而在高于700 ℃退火时,冷轧时的α取向-线织构痕迹逐渐减小,面织构的比率增加.取向分析表明,此时材料中存在较多的60.〈111〉孪晶的大角度晶界,由于孪晶成对称关系,导致材料的织构较弱.     

终轧温度对含钛铌超低碳铁素体不锈钢显微组织、织构和力学性能的影响

实验室研究了终轧温度对钛、铌复合添加的16%Cr超低碳氮铁素体不锈钢的显微组织、织构和力学性能的影响。结果表明,当终轧温度从940℃降低到800℃时,热轧退火钢板和冷轧退火钢板的铁素体晶粒尺寸均减小,因此采用低温终轧有利于细化铁素体晶粒。降低终轧温度,热轧退火后钢板中形成的γ纤维明显增强且比较均匀。由于织构具有遗传性,在冷轧退火钢板中也形成了均匀的γ再结晶织构。采用较低的终轧温度既有利于提高成型性又有利于改善材料的各向异性。     

固溶前退火温度对2519A铝合金棒材织构的影响

通过固溶前退火温度来调控2519A铝合金棒材固溶时的再结晶状态,以获得不同织构组态。采用X射线衍射分析研究了2519A铝合金棒材经150、200、300和350℃退火1 h后再经535℃×2 h固溶与直接经535℃×2 h固溶4种热处理工艺对合金织构和微观组织的影响。结果表明：2519A铝合金棒材直接经535℃×2 h固溶,挤压棒材强的〈13〉织构转变为〈110〉再结晶织构,而经上述4种温度退火和535℃×2 h固溶,织构分别演变为〈113〉,〈605〉,〈5110〉和〈7 214〉织构。退火后不固溶试样〈111〉织构和硬度值都保持不变。样品固溶发生再结晶的〈110〉织构与挤压〈13〉织构间可用40°〈111〉长大理论解释。     

终轧温度对443铁素体不锈钢组织、织构及成形性能的影响

通过光学显微镜、EBSD等分析技术,研究了终轧温度对443超纯铁素体不锈钢显微组织、织构、成形性能及抗表面起皱性能的影响规律。结果表明,降低终轧温度有利于促进443钢热轧退火态及冷轧退火态的再结晶,并使冷轧退火态组织更为细小均匀;降低终轧温度可有效强化冷轧退火态的γ纤维织构,是提高r值和杯突值、改善冷轧退火板成形性能、抗表面起皱性能的有效方式。     

退火温度对08Al冷轧板组织性能和织构的影响

在实验室条件下模拟罩式退火,运用金相显微镜、扫描电镜、微型控制电子万能实验机和X射线衍射仪研究了08Al冷轧深冲用钢不同退火温度（610～700℃）对其显微组织、力学性能和再结晶织构的影响。结果表明：在实验退火温度下,冷轧板在690℃的组织和综合力学性能最优,{111}〈UVW〉织构组分的百分含量最高,{111}〈UVW〉/{001}〈110〉的比值最大,所以在690℃08Al钢可获得最优的深冲性能。实验用钢在700℃退火组织中出现了大晶粒和对深冲性能有害的半网状和网状渗碳体,因此退火温度应该控制在700℃以下。     

退火温度对温轧Ti-IF钢板织构的影响

研究了冷轧后不同退火温度下温轧Ti-IF钢板的织构发展规律。结果表明:最佳退火温度为710～750℃。退火温度较低时(400～550℃),其织构类型与冷轧相同。退火温度为710℃和750℃时,得到了单一的强烈均匀分布的再结晶γ纤维织构,而退火温度为600℃和700℃时,虽然再结晶已经基本完成,部分α取向线上织构组分强度也迅速降低,但是再结晶γ纤维织构的强度并没有太大变化,说明在600℃和700℃退火时,消失的α取向的变形基体并没有完全被γ取向晶粒吞并,也转变成了其他取向的晶粒。     

终轧温度对铁素体不锈钢织构和成形性的影响

在实验室研究了终轧温度对铁素体不锈钢显微组织、织构和成形性的影响。结果显示,随着终轧温度的降低(从940℃到800℃),冷轧退火板的组织细化,γ再结晶织构强度增加,平均塑性应变比r值增加,平面各向异性Δr值降低。终轧温度的降低显著改善了薄板的成形性能。     

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.     

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。     

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).     

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.     

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.