等径角挤压铜合金的分节断裂（英文）

本研究提供了等径角挤压不同铜合金的局部剪切、坯锭开裂和分节断裂的实验依据。结果表明,尽管很多参数影响局部剪切,但是合金的硬度和分节断裂与其有着直接的关系,而硬度与合金的成分和相组成有关。在室温下,α-黄铜可以成功进行等径角挤压,而α/β黄铜甚至在350℃下都不能成功进行等径角挤压。利用DEFORM~(TM)软件模拟了开裂和分节断裂,研究不同参数对分节断裂的影响。结果表明,摩擦力和加工速率对获得完美坯锭影响很小,而利用背压可以很好地减小局部剪切、坯锭裂纹、分节断裂和破坏。利用背压能减小流动局部化,当背压由0提高到600Mpa时,可以提高材料流动均匀性并且使坯锭的均匀性提高36.1%。     

新型化渣剂AF3L~(TM)与AF3F~(TM)脱硫对比试验

对AF3F~(TM)、AF3L~(TM)新型化渣剂进行熔渣熔化特性测试、模拟铁水及钢水脱硫试验,对比研究分析了AF3L~(TM)的脱硫效果。通过试验结果发现加入AF3L~(TM)的渣系熔点更低,使得铁水、钢水脱硫反应更加透彻,持续时间更长,节约了用量和成本,提高了脱硫效率,这对于实际炼钢的生产具有非常重要的现实意义。但是在试验过程中加入了AF3L~(TM)化渣剂后有大量的有刺激性的白烟产生,通过试验分析得知白烟为含有氟化物的有害气体。     

HG70D高强钢焊接工艺研究

采用不同强度级别的焊丝对HG70D钢焊接接头进行了强度匹配工艺试验研究,试验过程中根据焊接接头强度匹配的原则,分别选用JM~(TM)-68、JM~(TM)-100、JM~(TM)-110等三种不同强度级别的焊丝进行焊接工艺试验研究,并研究了焊接接头力学性能。结果表明,采用JM~(TM)-100型焊丝焊接的接头与HG70D钢匹配性最佳。同时采用JM~(TM)-100型焊丝作为焊接材料,分别研究了在室温、预热90℃、预热150℃3种情况下力学性能,确定了HG70D的预热温度为90℃左右能够有效的避免焊缝区出现淬硬组织。     

固溶时效态Ti-Ni合金相变行为与Ni含量的关系

固溶淬火态Ti100-xNix合金中，x=40．0—49．O时，合金的马氏体相变(MT)温度(TM)、热滞(△TM)不变，相变热(△HM)升高；x=49．0—52．0时，合金的TM和△HM急剧下降，△TM急剧升高；x=52．0—56．0时，合金的TM和△HM升高，△TM降低；x=56．0—70．0时，合金的TM和△TM变化不大，△HM下降．673K时效态Ti1oo—xNix合金中，x=40．0—50．0时，合金发生MT，不存在时效效应；x=50．5—70．0时，合金既发生MT又发生R相相变(RT)且具有时效效应．随时效时间(tA)延长，TM和△HM先下降后上升，△TM下降．TR随x增加保持不变，随tA延长而升高．△TR对x和tA不敏感．△HR对z和TA都十分敏感．x=40．0—50．0和x=50．5—70．0合金的室温组织分别为M TiNi2和A(母相) 析出物．随x增加或tA延长，x=50．5—70．0的合金中析出物数量增多．     

宝钢BaoXM~(TM)镀层钢板在梅山基地首次试制成功

<正>2019年11月4日BaoXM~(TM)镀层钢板在宝钢股份梅山基地首次工业试制成功,这是宝钢锌铝镁系列产品(GalvAluMag~(TM))的又一重要突破。宝钢股份推出的GalvAluMag~(TM)系列产品根据镀层铝含量不同分为3大类:"低     

大应变轧制和均匀化处理对Mg-4Sn-1Mn合金力学性能和阻尼性能的影响

采用光学显微镜(OM)、维氏硬度、XRD、多功能内耗仪等,研究了各状态下的TM41镁合金的显微组织、硬度和阻尼行为.结果 表明,铸态、均匀化和轧制态TM41镁合金显微组织主要由α-Mg和Mg2Sn相组成;铸态TM41合金经均匀化处理后硬度改变不明显,但是大应变轧制后合金的硬度显著上升.在温度-阻尼谱中,轧制态TM41合...     

汉高向中国焊接工业推出新产品AERODAG~CERAMISHIELD~(TM)

<正> 汉高亚太区近日宣布向中国焊接工业推出新产品AERODAG~CERAMISHIELD~(TM)。AERODAG~CERAMISHIELD~(TM)产品运用了创新科技,能够极大地优化焊接工艺,在该领域是一款具有里程碑意义的产品。     

3D Systems发布新型高精度,高效金属打印设备 ProX~(TM) DMP 320

正大容量的金属增材制造方案可置换的打印模块增加通用性和生产力集中维护管理和连续制造工作流形成成本优势Rock Hill,南卡罗来纳州,2016年1月4日,3D Systems(NYSE:DDD)今天发布其商业化产品ProX~(TM) DMP320,这是3DSystems金属3D打印机产品线中添加的新成员。ProX~(TM)DMP320是专为需要打印复杂结构、高精度、高成型速度的纯钛、不锈钢或镍基超合金部件而设计的金属打印机。ProX~(TM)DMP 320为生产级金属打印提出了新标准。通过可置换的制造模块,ProX DMP 320可快速补充或变     

不同元素掺杂对Zr基非晶形成能力及力学性能的影响

在水冷铜坩埚中采用铜模吸铸法制备成直径为3 mm的Zr63Cu17.5Ni10Al7.5TM2(TM=Y,Fe,Ti)合金圆棒.通过X射线衍射(XRD)、差热分析(DSC)、力学性能及断口扫描(SEM)检测,结果表明Y、Fe、Ti元素微量掺杂可以得到完全非晶,Fe、Ti元素掺杂的试样具有较高的非晶形成能力和热稳定性(△...     

替硝唑口腔贴膜对实验性大鼠牙周炎的治疗作用及其对口腔粘膜刺激性研究

目的: 观察替硝唑口腔贴膜(TM)对实验性大鼠牙周炎的治疗作用及其对大鼠口腔粘膜的刺激性。方法: 用丝线缝扎大鼠上颌右侧第一磨牙、肌注醋酸强的松龙以及饲喂高糖水软饲料的方法造成实验性大鼠牙周炎模型, 将TM 贴敷于病变牙周部位,观察其对实验性牙周炎的治疗作用(TM 0.075 、0.175 、0.375 mg/只, 每日1 次, 连续7 d), 观察TM对正常大鼠口腔粘膜的刺激性。每次给予TM1.5 mg·cm^-2 (0.5 cm ×0.5 cm), 每日1 次, 连续7 d 。结果: TM 0.075 、0.175 mg 只对大鼠的口腔牙周软组织炎症有改善作用, 其疗效与阳性组(灌胃给药替硝唑100 mg·kg^-1)相似, TM 0.375 mg/只可使牙周软组织炎症明显减轻, 其疗效优于阳性组。对于牙周袋的形成及牙槽骨的破坏, TM 均无明显改善作用。对大鼠口腔粘膜无明显刺激作用。结论: 替硝唑口腔贴膜对实验性大鼠牙周炎有较好的治疗作用, 并且无粘膜刺激性。     

Simulation of the interaction between an edge dislocation and a 〈1 0 0〉 interstitial dislocation loop in α-iron

Atomic-level simulations are used to investigate the interaction of an edge dislocation with 〈1 0 0〉 interstitial dislocation loops in α-iron at 300 K. Dislocation reactions are studied systematically for different loop positions and Burgers vector orientations, and results are compared for two different interatomic potentials. Reactions are wide-ranging and complex, but can be described in terms of conventional dislocation reactions in which Burgers vector is conserved. The fraction of interstitials left behind after dislocation breakaway varies from 25 to 100%. The nature of the reactions requiring high applied stress for breakaway is identified. The obstacle strengths of 〈1 0 0〉 loops, 1/2〈1 1 1〉 loops and voids containing the same number (169) of point defects are compared. 〈1 0 0〉 loops with Burgers vector parallel to the dislocation glide plane are slightly stronger than 〈1 0 0〉 and 1/2〈1 1 1〉 loops with inclined Burgers vector: voids are about 30% weaker than the stronger loops. However, small voids are stronger than small 1/2〈1 1 1〉 loops. The complexity of some reactions and the variety of obstacle strengths poses a challenge for the development of continuum models of dislocation behaviour in irradiated iron.     

Effects of degree of deformation on the microstructure,mechanical properties and texture of hybrid-reinforced titanium matrix composites

Titanium matrix composites reinforced by TiB whiskers and La₂O₃ particles are synthesized in a consumable vacuum arc remelting furnace by an in situ technique based on the reaction between Ti, LaB₆ and oxygen in the raw material. The titanium matrix composites are hot rolled with degrees of deformation of 60%, 80%, 90% and 95%. The effects of the hot rolling degree of deformation on the mechanical properties of the composites are investigated by experiment and modeling. In particular, the variation in the inclination of the TiB whiskers during rolling is quantified in the model. The results show that, with increasing degree of deformation, the mechanical properties of composites are improved. Modeling of the mechanical properties reveals that grain refinement and TiB whisker rotation during rolling contribute to the improvement in the yield strength of the titanium matrix composites. Electron backscatter diffraction and transmission electron microscopy observations are used to study the texture of the composites. It is found that the orientation relationships between Ti matrix and TiB whiskers are [1 1 ?2 0]_Ti || [0 1 0]_TiB, (0 0 0 1)_Ti || (0 0 1)_TiB and (1 ?1 0 0)_Ti || (1 0 0)_TiB. TiB whiskers rotate in the rolling direction (RD) with increasing degree of deformation, which results in a higher intensity [1 1 ?2 0]_Ti || RD fiber due to the special orientation relationship between TiB and the Ti matrix.     

Study of the fracture behavior in soft and hard oriented NiAl single crystals by AFM

In order to understand the fracture behavior and room temperature brittleness of NiAl single crystals, atomic force microscopy (AFM) investigations were performed on in-situ loaded 4-point-bend specimens of hard and soft oriented crystals. A significant amount of dislocations are emitted from the crack tip on different slip systems. {1 0 0} slip planes are activated in soft crystals, whereas in hard crystals also slip planes, which are identified as {1 1 2} or {1 2 3} are observed. From evaluations of the AFM images, dislocation distributions ahead of crack tips and the plastic crack opening displacement (COD) from blunted crack tips are examined. The fracture toughness is calculated from the measured plastic COD and compared with the results obtained from load-displacement curves. First in-situ experiments on NiAl specimens heated up to 400 K are described, where a significant increase in plasticity is observed.     

Tensile strength of 〈1 0 0〉 and 〈1 1 0〉 tilt bicrystal copper interfaces

Molecular dynamics (MD) simulations are used to model dislocation nucleation at or near symmetric tilt bicrystal copper interfaces with 〈1 0 0〉 or 〈1 1 0〉 misorientation axes. MD simulations indicate that orientation of the opposing lattice regions and the presence of certain structural units are two critical attributes of the interface structure that affect the stress required for dislocation nucleation. Boundaries that contain the E structural unit are found to emit dislocations at comparatively low tensile stress magnitudes. A simple model is proposed to illustrate the impact of interfacial porosity and stresses acting on the slip-plane in non-glide directions on tensile interface strength. Accounting for interfacial porosity through an average measure is found to be sufficient to model the tensile strength of boundaries with a 〈1 0 0〉 misorientation axis and many boundaries with a 〈1 1 0〉 misorientation axis.     

Mechanism of polypyrrole and silver nanorod formation in lauric acid–cetyl trimethyl ammonium bromide coacervate gel template: Physical and conductivity properties

Polypyrrole (PPy) and silver (Ag) nanorods are synthesized in cetyl trimethylammonium bromide–lauric acid (CTAB–LA) complex coacervate gel template. When PPy–CTAB–LA system is polymerized with AgNO₃, Ag nanorods are produced while use of ammonium persulphate (APS) as initiator yields PPy nanorods. Ag-nanorods are produced from the initial stage while PPy nanorods take a longer time. The average diameter of Ag nanorods varies from 60 to 145 nm by increasing AgNO₃ concentration from 0.27 M to 1.08 M and that of PPy varies from 145 nm to 345 nm by changing pyrrole concentration from 1 × 10^?4 to 2 × 10^?4 M, respectively. Fourier transformed infrared (FTIR) spectra indicate stabilization of Ag nanorods through complexation of PPy with adsorbed Ag⁺ ions. PPy nanoparticles are stabilized by adsorbed sulphate ions and lauric acid, both are acting as dopant to it. FFT pattern and EDX spectra clearly indicate the presence of Ag nanocrystals and PPy on the surface of Ag nanorods, respectively. The mechanism of nanorod formation is attributed from UV–Vis spectra showing a red shift of surface plasmon band of Ag and π–π* transition band of PPy with time. The highest dc conductivity of PPy–Ag composite is found to be 414.2 S/cm, 7 orders higher than that of PPy nanorods (9.3 × 10^?4 S/cm). PPy–Ag systems show Ohmic behavior while PPy nanorods exhibit semi-conducting behavior. The preferential formation of Ag nanorod in AgNO₃ initiated polymerization is attributed to the higher cohesive force of Ag than that of PPy. With two times higher LA and CTAB concentration in the gel the Ag nanorod diameter decreases only 12% while that of PPy nanorod decreases by 50%. Possible reasons are discussed from the hard and soft nature of the two nanorods and from the elasticity of the gel template.     

Atomic structures of symmetrical and asymmetrical facets in a near Σ = 9{2 2 1} tilt grain boundary in copper

Atomic structures in a Σ = 9{2 2 1} tilt grain boundary (GB) grown by Bridgman solidification of a tricrystal are determined through high-resolution transmission electron microscopy and numerical simulation. Atomic models are simulated via molecular dynamics annealing using an n-body potential fitted on copper properties including its stacking fault energy. Symmetrical and asymmetrical facets are thus identified. Mainly asymmetrical facets are observed, namely Σ = 9{11, 11, 1}||{1 1 1} and also small parts of incommensurate {1 1 0}||{1 1 1}. The symmetrical facets are described by a quasi-mirror plane atomic structure. A specific GB structural unit is recognized as a Lomer unit. Its GB Burgers vector depends on the GB structure itself. Further analyses of these models and of accommodating dislocations are successfully carried out at the atomic level within the framework of the continuous structural unit approach.     

Inter-martensite strain evolution in NiMnGa single crystals

Stress-induced martensitic transformations are clarified in classes of NiMnGa alloys which undergo the stress-free, thermal-induced inter-martensite transformation austenite (A) ⇌ pre-martensite (PM) ⇌ martensite. This study implements a comprehensive experimental approach, including analysis of the strain–temperature and stress–strain response, which discloses stress-induced inter-martensite transitions. The evolution of the transitions is elucidated using in situ digital image correlation (DIC) measurements of meso-scale strain fields. Under stress, this body of work unequivocally demonstrates that the transformation path becomes A ⇌ PM ⇌ I ⇌ 10M. The I-phase is an intermediate stress-induced martensite with a modulation period between three and five-layers. Owing to the intermediate transition, the thermal hysteresis in the strain–temperature response is tiny (<10 °C) compared with the hysteresis (32 °C) for A ⇌ 10M. The differential hysteresis levels are rationalized based on a thermo-mechanical formulation. Meso-scale DIC measurements quantify inter-martensite strain levels, which are indistinguishable from macro-scale stress–strain and strain–temperature responses.     

NiSi2/Si interface chemistry and epitaxial growth mode

Epitaxial NiSi₂ thin films are formed by annealing of Ni on sulfur-implanted silicon (1 0 0). The atomic structure and chemistry of the NiSi₂/Si interface are investigated by aberration-corrected transmission electron microscopy. The interface is atomically sharp and runs mainly along the (1 0 0) plane. {1 1 1} segments of interface are also observed as minor facets. The atomic structure of the (1 0 0) and (1 1 1) interface has been determined. Interfacial dislocations with Burgers vectors a/4<1 1 1> and a/2<1 1 0> are observed near {1 1 1} facets. In particular, these dislocations have extra half atomic planes in the Si substrate. This configuration of dislocation does not agree with the sign of the lattice mismatch between bulk NiSi₂ and Si. This novel phenomenon is understood by the fact that a high concentration of sulfur in the interface area leads to an expansion of the NiSi₂ lattice and thus inverts the sign of the lattice mismatch. It is suggested that the change of the strain status, in addition to the doping effect of S, also plays a role in the tunable Schottky barrier height in this system.     

Correlation of the atomic and electronic structures and the optical properties of the Σ5(2 1 0)/[ 0 01] symmetric tilt grain boundary in yttrium aluminum garnet

A series of atomic models of the Σ5(2 1 0)/[0 0 1] symmetric tilt grain boundary in yttrium aluminum garnet (YAG) are constructed according to the coincident site lattice theory. Calculations performed using empirical potentials show that the O-termination configurations, namely G(1) and G(2), are the most energetically favorable boundary structures. First-principles density functional theory calculations have been further performed to understand the atomic and electronic structures, effective charge, potential distributions and optical properties of G(1) and G(2) grain boundaries. The simulated high-resolution transmission electron microscopy images of G(1) and G(2) are generally in good agreement with the experimental micrographs of the Σ5(2 1 0)/[0 0 1] grain boundaries. Results show that the effective charges of the atoms in the grain boundary region are related to their coordination numbers and bonding lengths. Moreover, the overall total density of states of G(1) and G(2) has been found to have similar features with the bulk YAG, with the exception of some defect states being introduced at the top of the valence band, resulting in the reduction of the band gap. The calculated optical properties show that the refractive indices of both grain boundary models are slightly larger than those of the bulk YAG. This is in agreement with the experimental observation that the refractive index of the polycrystalline YAG is higher than that of its single crystalline counterpart.     

Creep microstructures and creep behaviors of pure molybdenum sheet at 0.7 Tm

The creep behavior of high purity molybdenum (99.995 wt.%) is investigated at temperatures of 1600 to 2000 °C (0.61–0.77 T_m) by direct ohmic heating. The stress and temperature dependency of creep strain and rupture time are described through optical microstructure observations. Under low load and low temperature conditions, coarse secondary recrystallized grains caused by dynamic recrystallization are observed far from the crack tip. In contrast, under high load and high temperature conditions, coarse secondary recrystallized grains are only fully formed near the crack tip, while coarse secondary recrystallized grains and small primary recrystallized grains coexisted further away from the tip. The recrystallized grain size of the Mo-B sheet is smaller than that of the Mo-A sheet, and small primary and large secondary recrystallized grains are mixed throughout whole specimens of the Mo-B sheet. Mo-A sheet shows elongated ductile fracture, but Mo-B sheet shows irregular brittle fracture under the same conditions. The steady-state creep strain rate at 1800 °C is found to be 7.34 × 10^− 6, 2.83 × 10^− 5 and 1.53 × 10^− 4 s^− 1 under a constant stress of 5, 10 and 20 MPa, respectively. The stress exponent is estimated to be 3.85–3.98 and the strain activation energy for steady state creep is 362–413 kJ/mol.