低温球磨和真空热压技术制备的纳米晶纯铝块体的强化机理

利用液氮球磨和真空热压技术制备了纳米晶纯铝块体材料。采用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对材料的晶粒尺寸和微观组织进行研究,分析了影响热稳定性的因素和强化机理。研究表明,液氮球磨以后材料晶粒尺寸为37nm,经过真空热压和热挤压后晶粒有所长大,晶粒大小约300nm,纳米晶结构基本得到保持。分析晶粒热稳定性的原因在于球磨过程中生成的AlN等粒子的晶界钉扎以及引入的杂质溶质的拖拽作用。纳米晶纯铝块体的拉伸强度极限σb为173MPa,伸长率fε为17.5%。     

固化球磨纳米晶粉末制备块体超细晶Mg-3Al-Zn合金(英文)

采用粉末冶金技术制备块体超细晶Mg-3Al-Zn合金。首先采用球磨Mg、Al、Zn混合粉末来制备纳米晶粉末,所得的粉末的平均晶粒尺寸为45nm。随后将球磨好的粉末封入铝包套内,分别在室温和633K温度下,在真空烧结炉内进行真空热压。然后将烧结后的样品在423K下挤压以进行进一步的致密化处理。结果表明:致密后的冷压样品的晶粒尺寸为180nm,而热压坯的晶粒尺寸为600nm,冷压样品的屈服强度达464MPa;超细晶镁合金的强化机制主要是细晶强化,这主要是由于HCP结构的材料晶粒尺寸对材料的影响更为明显。固化后冷压样品的最终密度为(1.777±0.006)g/cm3,而热压样品的最终密度为(1.800±0.006)g/cm3。     

块体纳米晶Al-Zn-Mg-Cu合金的热处理

利用液氮球磨、真空热压和挤压工艺制备块体纳米晶Al-Zn-Mg-Cu合金,并对其固溶和时效处理进行研究,得到时效硬度曲线。利用X射线衍射仪和透射电镜对该合金热处理前后的微观组织进行分析,结果表明:块体制备过程中析出的MgZn2可以通过固溶处理使其回溶并在时效后沉淀析出;热压后晶粒尺寸为50~100 nm,热处理后晶粒长大到100 nm,部分晶粒达到200 nm。     

低温球磨纳米晶Al-Zn-Mg-CU合金组织的演变

利用液氮低温球磨技术制备了纳米晶Al-Zn—Mg—Cu合金粉体,分析了材料在球磨过程中微观组织变化．结果表明,气雾化Al—Zn—Mg—Cu合金粉体随着球磨过程的进行晶粒尺寸逐渐减小,球磨15h后晶粒尺寸约为35nm;MgZn2相逐步分解,并最终过饱和固溶于α—Al中．制备的纳米晶Al—Zn—Mg—Cu合金粉体低于709K（0．77Tm,Tm为熔点）加热时,晶粒长大速度缓慢;709K加热1h晶粒尺寸仅为71nm．研究表明,液氮低温球磨过程中形成的Al2O3颗粒对晶粒的钉扎有效地提高了纳米晶Al-Zn—Mg—Cu合金粉体的热稳定性．     

低温球磨制备纳米晶Al-Zn-Mg-Cu合金粉末的热稳定性研究

利用液氮球磨技术制备了纳米晶Al-10Zn-3Mg-1．8Cu（wt％）合金粉体材料。采用X射线衍射（XRD）、透射电镜（TEM）和差热分析仪（DSC）对材料在制备过程中的固态相变、晶粒尺寸和热稳定性进行了分析。结果表明，液氮球磨10h后Al—10Zn-3Mg-1．8Cu粉末晶粒达到45nm，微观应变随着球磨的进行逐渐增大。球磨过程中MgZn2和CuAl2相逐渐消失，合金元素超饱和固溶于α—Al之中。球磨粉末热处理过程中发生了回复和再结晶。球磨产生的大量微观应变和热处理时第二相的脱溶都降低了回复激活能，使回复温度下降。包括晶粒的长大、聚集位错的减少、孪晶、点缺陷和非平衡晶界等因素导致回复放热量增加。粉末晶粒的细化、细小Al2O3粒子的生成和第二相的脱溶析出则抑制了再结晶过程，使再结晶温度升高。纳米晶粒在436℃（0．77Tm）发生异常长大，合金粉末经过球磨后具备了较高的热稳定性。     

液氮球磨Sm-Fe合金的组织演变

利用低温液氮球磨技术制备了Sm-Fe合金粉体,采用XRD、HRTEM和惰性气脉冲-红外-热导等方法对Sm2Fe17合金粉体在液氮球磨过程中的组织演变进行了研究。结果表明,液氮球磨可加速细化Sm-Fe合金粉体。球磨5 h后,Sm-Fe合金的晶粒尺寸约为10 nm,9 h后晶粒尺寸约为5 nm。Sm-Fe合金中的氮含量随着球磨时间的延长而增加,主轴转速150 r/min球磨9 h后,氮含量达1.62% (质量分数, 下同)。随着球磨时间的延长,Sm2Fe17相向非晶态转变,降低球磨转速可以延缓非晶的形成过程     

合金化元素对纳米晶铝合金热稳定性的影响

为研究加入Fe和Ti扩散系数有限的元素对纳米晶铝合金热稳定性的影响,制备Al?10%Fe(质量分数)和Al?10%Fe?5%Ti(质量分数)合金。将初始混合粉末在真空下球磨100 h,用高频感应加热烧结系统将球磨后的粉末制备成块体样品。采用X射线衍射仪、维氏显微硬度仪、场发射扫描电子显微镜和透射电子显微镜对球磨后的粉末和烧结后的块体样品进行表征。结果表明,Fe和Ti完全分散在基体中,与Al形成过饱和固溶体。另外,合金元素的加入使合金的硬度和屈服强度分别提高127%和152%。通过高温压缩试验评估合金的热稳定性,结果显示3种合金样品中Al?10%Fe?5%Ti合金的热稳定性最好。Fe和Ti的加入抑制合金的晶粒长大,阻碍第二相如Al13Fe4和Al13Ti的分解、长大,形成稳定的固溶体,从而提高合金的热稳定性。     

机械合金化及真空热压制备纳米晶Fe3Al的组织及性能

采用机械合金化(MA)及热压烧结工艺制备纳米晶Fe3Al块体材料。采用X射线衍射、透射电镜、扫描电镜等对MA粉体及热压块体的相及显微组织进行分析,并对热压块体的力学性能及断口形貌进行了测试分析。结果表明:Fe72Al28混合粉在球磨过程中,Al逐渐溶入Fe中,形成Fe(Al)过饱和固溶体,纳米晶粉体的结构有序度较低。在1200℃,保温1h下真空热压烧结,Fe(Al)转变为有序的DO3-Fe3Al,同时发生晶粒长大。Fe3Al块体晶粒尺寸为40.1nm,相对密度大于96%,维氏硬度626.8 HV,三点弯曲强度985MPa;弯曲断口为脆性断口,但也呈现出一定韧性断裂特征。     

粉末冶金Nb-35Ti-6Al-5Cr-8V合金组织演变及其力学行为

采用粉末冶金法对不同球磨时间的Nb-35Ti-6Al-5Cr-8V合金机械合金化粉末塑变行为,热压烧结材料的微观组织结构和力学行为进行了研究。研究结果表明：塑性良好的Nb-35Ti-6Al-5Cr-8V粉末随着球磨时间增加首先变形为大尺寸的片状、后经持续的加工硬化破碎成絮状;热压烧结能够制备微观组织可控晶粒细化的Nb-35Ti-6Al-5Cr-8V合金,合金由单一的Nbss相构成,Ti、Al、Cr、V元素固溶引起Nb晶格尺寸减小0.0685 ?;随着球磨时间增加合金晶粒明显细化进而显著提高了合金的维氏硬度和室温压缩强度,其变化符合材料硬度和强度的Hall-Petch规律。粉末冶金制备Nb-35Ti-6Al-5Cr-8V合金的各项力学性能明显优于熔铸法制备合金。     

双步球磨法制备纳米晶结构TiAl基合金粉末的研究

以元素粉末为起始粉末,采用双步球磨法(球磨+热处理+球磨)制备TiAl基纳米晶多相结构粉末(粉末成分为Ti-47Al(at%)、Ti-45Al-2Cr-2Nb-1B-0.5Ta(at%)).采用xRD、SEM、EDs、DTA、粒度分布仪对两种粉末颗粒在球磨和热处理过程中的特性进行了表征和分析.结果表明,采用双步球磨法制备的多相结构纳米晶粉末杂质含量低,粒度分布均匀,合金元素弥散分布.一步球磨6 h获得Ti/Al均匀复合结构及实现Ti(Al)部分固溶;700℃,2 h热处理获得Ti3Al、Ti、Al3Ti、TiAl相,Al相已经消失;二步球磨实现晶粒尺寸、颗粒尺寸进一步细化.     

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.     

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.     

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.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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