MgO/Mg2Si增强Mg-Li基复合材料的界面结构

通过液态原位反应合成制备MgO/Mg2Si增强Mg-Li基复合材料,利用TEM对增强相形态及界面结构进行了观察.实验结果表明,复合材料中增强粒子与基体界面结合良好,无反应物生成.确定了增强粒子与基体的界面取向关系,MgO与基体α相的晶体学关系为[100]MgO//[40（￣4）3]α,（011）MgO//（（￣1）2（￣1）0）α;Mg2Si与基体β相的晶体学关系为[310]Mg2Si//[411]β,（1（￣3）（￣1））Mg2Si//（001）β.     

CuO涂覆Mg2B2O5晶须增强镁基复合材料界面结构研究

采用溶胶-凝胶法制备的CuO涂覆Mg2B2O5晶须改善了晶须增强镁基复合材料的界面。利用X射线衍射仪、扫描电镜和透射电子显微镜对CuO涂覆Mg2B2O5晶须和镁基复合材料分别进行物相分析、形貌观察和界面结构分析。结果表明:CuO成功地涂覆在了Mg2B2O5晶须上,CuO涂覆Mg2B2O5晶须增强镁基复合材料的界面相为MgCu2和MgO相,来源于CuO和基体的界面反应产物;基体析出相MgZn2在晶须两侧平行生长,在特定位置和晶须具有一定的晶体学位向关系:[001]Mg2B2O5[5143]MgZn2和(100)Mg2B2O5(0111)MgZn2;CuO涂覆Mg2B2O5晶须增强镁基复合材料的抗拉强度和伸长率分别提高了37.6%和35.7%。     

Mg2B2O5晶须增强镁基复合材料的组织与界面结构研究

采用光学显微镜、透射电子显微镜和X射线衍射仪研究Mg2B2O5晶须增强镁基复合材料的铸态组织及Mg2B2O5/AZ91D界面反应产物。结果表明:Mg2B2O5晶须具有孪晶结构,其孪生面和晶体生长方向分别为(202)和[010];部分Mg2B2O5晶须中存在MgB4O7颗粒相;在基体晶界与Mg2B2O5晶须之间存在等轴状Mg2Si相;Mg2B2O5/AZ91D界面处存在厚度不均匀的MgO和MgB2相界面层。尽管Mg2B2O5、MgO和MgB2之间没有确定的晶体学位相关系,但在特定Mg2B2O5晶须表面观察到(202)Mg2B2O5//(002)MgO,[010]Mg2B2O5//[110]MgO和(002)MgO//(0001)MgB2,[110]MgO//[2110]MgB2取向关系。最后,讨论Mg2B2O5晶须对复合材料组织结构和性能的影响。     

浸渍/挤压(SiCw+B4Cp)/Mg(AZ91)复合材料的界面特征

用透射电子显微术研究了 (SiCw B4Cp) /Mg(AZ91)复合材料的界面特征。结果表明 :B4Cp/Mg界面区反应生成物混乱 ,而在SiCw/Mg界面区较为规则。SiCw/Mg界面生成了两种反应物 ,其中MgO与SiC具有 180 旋转孪晶关系 ,孪晶面为 { 111} SiC ,MgO,而MgB2 一般以SiC表面一薄层MgO为基底生长成较大且完整的晶形 ,MgB2 与MgO之间的晶体学取向关系为 :(1—11) MgO∥ (0 0 0 1—) MgB2 ,[110 ]MgO∥ [112 —0 ]MgB2 。高分辨观察结合计算机模拟确定了MgO/MgB2 界面有两种原子占位方式 ,一种为界面处有两层Mg原子分别属于两相 ,另一种为界面处只有一层Mg原子为两相共享。此外 ,基体中第二相Mg17(Al,Zn) 12 和未知弥散小颗粒均与基体Mg非共格     

Mg2B2O5w/AZ91D镁基复合材料的界面结构及其形成机理

采用X射线衍射仪、X射线光电子能谱仪、扫描电子显微镜和透射电子显微镜对萃取Mg2B2O5w的物相、表面元素化学状态变化及Mg2B2O5w/AZ91D复合材料界面反应产物进行了研究.结果表明:Mg2B2O5w/AZ91D界面处存在厚度不均匀的MgO和MgB2相界面层;MgO的形成主要与复合材料制备过程中晶须表面上的吸附氧有关,而界面产物MgB2则应来源于Mg2B2O5w分解产物B2O3与基体中Mg的反应;Mg2B2O5w、MgO和MgB2之间通常没有确定的晶体学位相关系,但在特定Mg2B2O5w表面观察到(202)Mg2B2O5w//(002)MgO,[010]Mg2B2O5//[110]MgO和(002)MgO//(0001)MgB2,[110]MgO//[2110]MgB2取向关系.     

用相变晶体学指导Mg-Sn-Mn合金优化设计

以相变晶体学为主要原则对Mg-Sn-X合金进行优化设计.在对现有镁合金系统充分调研的基础上,根据Mg基体与析出相的相变晶体学匹配关系,提出2条相变晶体学判据来判断可能沿Mg基体[0001]α方向择优生长的析出相.根据这2条相变晶体学判据结合相图分析推测在Mg-Sn-Mn系统中可能得到沿Mg基体[0001]α方向择优生长...     

(SiCW+B4Cp)/MB15 Mg基复合材料的微观结构

利用高分辨电镜研究了(SiCw+B4Cp)/MB15 Mg合金基复合材料的微观结构.SiC晶须的表面附着呈截角八面体形状的MgO纳米颗粒.此外,MgB2和MgO共生在SiC晶须的表面,三者之间存在固定的晶体学取向关系[110]SiC∥[110]MgO∥[1120]MgB2和(111SiC∥(111MgO∥(0001MgB2.MgB2相呈六角盘状几何外形,在Mg合金中其界面能的各向异性显著.此外,还发现了SiC和Mg存在的一种晶体学取向关系[111]siC∥[0001]Mg和(202)siC∥(1120)Mg.研究结果表明,在Mg合金复合材料中,SiC比B4C更加稳定.     

多元氧化物和铝原位反应制备铝基复合材料的组织和性能

采用SEM、EDS、XRD、TEM和拉伸强度测试等研究Al2O3粒子增强的ZL109铝基复合材料。结果表明:多元氧化物和铝原位反应生成的Al2O3粒子尺寸细小,粒径约为0.1μm,在基体中弥散分布,与基体存在共格关系,(001)α(Al)//(010)α-Al2O3,[110]α(Al)//[001]α-Al2O3。原位反应中生成的金属间化合物经T6处理后,以Al5FeSi、FeCr、Mg2Si、Al3Ni、Al2Cu和Al7Cu4Ni相的形式存在于基体中,使得复合材料在300℃的拉伸强度达到163.4 MPa,较基体的提高7.9%。随Al2O3粒子含量的增加,25℃时,复合材料断口断裂方式由韧性断裂转变为解理断裂,再到穿晶断裂;而300℃时,断口断裂转变方式为脆性断裂到延性断裂。     

原位反应自生MgO/Mg2Si增强镁基复合材料的热力学和动力学研究

对SiO2与Mg反应的热力学分析计算，在Mg的熔化温度范围内，Mg与SiO2反应生成MgO和Mg2Si。通过真空感应炉中氩气保护，在纯Mg熔体中加入SiO2原位反应自生MgO／Mg2Si增强镁基复合材料，并采用XRD、OM、ESEM、EDAX等对反应生成相的种类、形态、大小和分布等进行研究。结果表明：800℃在Mg中加入SiO2可原位反应生成Mg2Si和MgO增强相，Mg2Si为多角形和细条状，在Mg基体中分布均匀；MgO为细小的粒子状，在熔体中分布不均匀，大多则是聚集在坩蜗底部；机械搅拌可有效削弱反应添加物SiO2的动力学沉降过程，改善原住反应的动力学条件，促使反应生成的MgO在熔体中分布均匀.初步建立起SiO2与Mg反应的宏观动力学模型。     

原位合成Mg_2Si/Mg-2Al-Zn-2Gd复合材料的微观组织与断裂行为

采用多次循环塑性变形-原位反应方法制备Mg2Si/Mg-2Al-Zn-2Gd复合材料。采用XRD、SEM和TEM对复合材料的成分及微观组织进行分析和观察。结果表明:多次循环塑性变形过程对镁合金基体组织和原位合成的Mg2Si第二相粒子均有细化和均化作用;随着Mg2Si颗粒含量的增加,复合材料的弹性模量和屈服强度增加,同时断裂强度和伸长率均下降;原位反应合成的Mg2Si第二相粒子与基体结合良好,材料断裂时裂纹优先在基体中形成,断裂时Mg2Si第二相粒子能起到阻碍裂纹扩展的作用;Mg2Si/Mg-2Al-Zn-2Gd复合材料的强化机制主要为第二相强化和基体晶粒细化。     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.     

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.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.