Time-resolved probe diagnostics of pulsed DC magnetron discharge during deposition of TiOx layers

The paper presents an experimental study of a pulsed DC unbalanced magnetron discharge with Ti target. This system is being used for deposition of nanocrystalline TiO_x thin films. The unbalanced magnetron was operated in pulsed regime with the low repetition frequency of modulation cycle ν_p = 250 Hz and relatively short active part of modulation cycle T_a = 150 μs. Low average discharge current was used with maximum value about 1 A. Maximum instant discharge current in the active part of modulation cycle was 20 A. Relatively high plasma density up to value n_e ≈ 10¹⁸ m^− 3 was achieved at these conditions but due the low average power absorbed in the plasma the heat load applied on the target and the substrate was low. Time-resolved and spatially resolved Langmuir probe diagnostics was used for the systematic and detailed experimental study of the system. Experimental conditions as the instant value of discharge current, gas pressure in the reactor, gas mixture ratio Ar/O₂, etc. were varied in a broad range. The time evolutions of plasma parameters such as electron density, electron temperature, plasma potential and EEPF were determined during the modulation cycle of pulse discharge excitation.     

Effect of interstitial hydrogen and nitrogen on the magnetocrystalline anisotropy of Y2Fe17

Magnetocrystalline anisotropy of Y₂Fe₁₇ and of its nitride and hydrides has been measured on magnetically oriented samples. The anisotropy is defined by the local site anisotropy behavior and in a first approximation depends mainly on the lattice expansion along the c axis.     

含有{111}织构的纳米孪晶多晶铜在拉伸变形过程中塑性各向异性机制的分子动力学模拟

基于分子动力学模拟,从主导滑移系的斯密特因子和位错机制两个方面系统研究含有{111}织构的纳米孪晶多晶铜在拉伸变形过程中的塑性各向异性机制.结果表明:主导滑移系的斯密特因子随着孪晶界倾角的改变而变化,但屈服应力或流动应力并不严格遵守斯密特定律.在拉伸变形过程中存在涉及不同位错机制的硬取向和软取向.硬取向的硬化机制在于塑...     

Theoretical analysis on the effects of crystal anisotropy on wiresawing process and application to wafer slicing

Most of the crystals sliced using wiresaw are anisotropic to an extent. The effect of crystal anisotropy on the process of slicing using wiresaw is studied and presented in this paper. A method is proposed to determine the direction of approach (DOA) which will give a better surface finish and reduce deviation from the desired surface normal by maintaining symmetry in material removal rates on the two sides of the wire. The effect of cleavage anisotropy on wiresaw slicing is also studied. If the DOA is perpendicular to a cleavage direction, then the longitudinal direction of the wire aligns with the cleavage direction which increases the tendency of wafer breakage, resulting in lower yield of the wafers. This can be easily avoided by choosing an appropriate DOA. Theoretical analysis is carried out using the proposed methods for slicing silicon wafers. Recommendations are made for three most commonly sliced orientations of silicon: (100), (110) and (111). DOA can be any direction for (100) and (110) wafers from the symmetry point of view but preferred DOAs do exist for these wafers from cleavage point of view. For (111) crystal there are exactly six DOAs with symmetry. However, these six DOAs do not lie in the preferred zones suggested by cleavage criterion. It is suggested that in such situations the symmetry criterion should be given precedence over the cleavage criterion during wiresawing process, as the semiconductor industry has strict tolerances in place for surface normal deviation and flatness.     

AZ31镁合金挤压薄板织构及力学各向异性

研究AZ31镁合金挤压薄板的显微组织、织构及室温下板面内各不同方向的力学性能。织构分析表明,挤压薄板主要有{0002}<1-010>和{10-10}<11-20>2种织构组分。拉伸测试结果显示,沿挤压方向屈服强度最高,达到200.4MPa,这是由于这种取向基面滑移和{1-012}锥面孪生均不能开动,发生织构强化的结果;与挤压方向呈45°方向伸长率最高达19.0%,这是由于具有{10-10}<11-20>织构组分晶粒的基面滑移开动;与挤压方向呈90°方向屈服强度最低仅为挤压方向相应值的一半左右,这是由于具有{10-10}<11-20>织构组分晶粒发生了{10-12}锥面孪生。     

规则多孔铜的拉伸性能及其各向异性

采用固-气共晶定向凝固的方法制备规则多孔铜,研究其室温拉伸性能的各向异性和气孔率对拉伸力学性能的影响,建立表征抗拉强度与气孔率和拉伸方向相关的数学模型.结果表明:规则多孔铜的拉伸性能主要取决于材料的气孔率和拉伸方向;随着气孔率的增大,规则多孔铜的拉伸性能明显下降:规则多孔铜拉伸性能呈各向异性特征,0°方向性能最好,45°方向的次之,90°方向的最差;各拉伸方向的实验数据与模型数据吻合良好.断口分析表明:规则多孔铜呈韧性断裂,拉伸断裂从孔壁处开始,最终因颈缩导致完全断裂.     

AZ31镁合金的各向异性及断裂行为

研究织构和异常长大晶粒对热轧AZ31镁合金力学各向异性和断裂行为的影响.在拉伸轴与板材的法向方向分别呈0°、15°、30°、45°、60°、75°和90°下进行单轴拉伸实验,观察不同角度下样品的拉伸各向异性.结果表明:由于{1012}孪晶的出现,在0°-30°时样品表现出较低的屈服强度;当角度大于45°时,样品的主要的变形机制为基面和柱面滑移;当角度低于60°时,宏观断口平行于大晶粒拉长的方向;在75°和90°时样品的宏观断口呈锯齿状.     

Magnetocrystalline anisotropy and spin reorientation transition of DyMn6Sn6 compound

The spin-reorientation transition of intermetallic compound DyMn6Sn6 was investigated by applying the molecular field theory. The temperature dependence of easy magnetization direction of compound and the magnetic moment directions of Dy and Mn ions were theoretically calculated and they have good agreement with the experimental data. In the framework of single ion model, the temperature dependence of magnetocrystalline anisotropic constants K1R and K2R of Dy ion were also calculated. The results show that the fourth-order crystal field parameter, B 40, and the corresponding second-order magnetocrystalline anisotropic constant, K2R, of Dy ion must be taken into account in order to explain the spin-reorientation transition satisfactorily. The competition between K2R and K1R plays a key role in the spin-reorientation transition of DyMn6Sn6.     

Ti70合金板的组织与力学性能的各向异性

通过拉伸及低温冲击试验、光学显微镜、扫描电镜及X射线衍射仪,对Ti70合金板的组织与力学性能的各向异性进行了研究。结果表明,Ti70合金板热轧及退火后组织未出现明显差异,退火过程中主要以回复为主,但在高密度位错的剪切带上出现了一定数量的再结晶晶粒。退火态Ti70合金板横向屈服强度及低温冲击吸收能量都高于纵向,但抗拉强度低于纵向,表现出了明显的各向异性。退火后Ti70合金板形成了较强的{0002}基面织构,其晶面法向向RD方向(纵向)偏转±30°,向TD(横向)方向偏转±41°。由于基面织构更向RD方向集中,因此造成了Ti70合金板力学性能的各向异性。     

Strengthening contribution of precipitates and anisotropy of yield strength in Al-Li alloys 2090 and 2090 Ce

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退火温度对高强IF钢平面各向异性的影响

通过对轧制态的含磷Nb-Ti高强IF钢冷轧硬卷进行750～870℃退火试验,在Instron5569拉伸试验机上测试计算了塑性应变比r值和平面各向异性指数Δr,并对不同退火温度下的试样进行了ODF分析。结果表明,退火温度从750℃升高到870℃,试验钢的r0、r45、r90和珋r均随温度的升高而增大;平面各向异性随退火温度的升高而降低。结合显微组织分析,810～840℃退火时,试验钢获得最佳综合性能。试验钢从冷轧态到完全再结晶,{001}<110>、{110}<110>织构强度降低,{112}<110>织构遗传成为最强织构,而{111}<110>织构比{111}<112>织构强,使Δr值为负值;最佳退火温度(810～840℃)条件下最大珋r值为1.65,Δr为-0.38。     

铝-镁-钪合金板材晶粒结构、织构和力学性能平面各向异性

采用力学性能测试、XRD织构测定、金相和电子显微分析,研究了铝-镁-钪合金热轧态板材与冷轧-退火态板材在不同取向条件下的组织与性能。结果表明,合金板材在与纵向成30°的方向以及横向的强度比纵向强度高,45°和60°方向的强度则较低,伸长率则是30°方向的最低、45°方向的最高,合金板材表现出反常的力学性能平面各向异性。认为{110}<112>织构的存在和沿轧制方向延展的煎饼状晶粒组织是造成这种合金板材反常平面各向异性的主要原因。     

超细晶钢微观组织与力学性能的各向异性研究

通过温轧技术,成功制备了平均晶粒尺寸约1μm的超细晶钢。利用扫描电镜、电子背散射衍射和室温拉伸等检测手段,研究了超细晶钢板的微观组织与力学性能的各向异性。结果表明：制备的超细晶钢板不同方向的微观组织和力学性能具有明显的各向异性;纵截面表层和心部的晶粒大多呈现拉长的形态,同时表层的晶粒拟合椭圆长/短轴比相较于心部更小,形状更加接近于圆形,横截面的晶粒拉长状特征相较于纵截面减弱,更接近等轴态,晶粒在三维空间呈细长的扁梭形态;各向强度由高到低依次为轧向、横向、与轧向成45°方向;长梭形晶粒组成的微观组织形态和织构是导致超细晶钢板力学性能各向异性明显的主要原因。     

Phase field model for strong anisotropy of kinetic and highly anisotropic interfacial energy

A phase-field model was established for simulating pure materials, which was calculated effectively and taken into account the strong anisotropy of kinetic and highly anisotropic interfacial energy. The anisotropy （strong kinetic and highly interfacial energy） of various degrees was simulated with numerical calculation. During a variety of interfacial anisotropy coefficient, equilibrium crystal shape varies from smoothness to comer. There has a critical value during the course of the transformation. When the anisotropy coefficenct is lower than the critical value, the growth velocity v increases monotonically with the increase of it. Whereas the anisotropy coefficent is higher than the critical value, the growth velocity decreases with the increases of it. During a variety of degree of supercooling, the growth velocity is under control from thermal diffusion to kinetics. Under the control of thermal diffusion, the growth velocity increases with the increase of degree of supercooling and tip radius R decreases with the inca＇ease of temperature. Under the control of kinetics, with the increase of degree of supercooling both V and R, which can not fit the traditional microcosmic theory.     

Influence of different rolling routes on mechanical anisotropy and formability of commercially pure titanium sheet

Influence of three different rolling routes on mechanical anisotropy and formability of commercially pure titanium sheet was investigated. Route A and Route B are unidirectional rolling (UR) where the rolling direction is along initial rolling direction (RD) and transverse direction (TD), respectively. Route C is cross rolling (CR) where the rolling direction is changed by 90° after each rolling pass. The microstructure and texture, tensile mechanical properties including strength and elongation, and also the anisotropy of the UR and CR sheets were investigated at room temperature. The XRD results indicate that the texture intensity of rolled samples gradually weakens from Route A to Route C. Compared with Route A and Route B rolled samples, the Route C rolled samples show a smaller planar anisotropy. The deep drawing tests reveal that cross rolling can avoid the occurrence of earing. Erichsen tests indicate that rolling routes have an effect on stretch formability of pure titanium sheet.     

Influence of rolling ways on microstructure and anisotropy of AZ31 alloy sheet

Two rolling ways,unidirectional rolling and cross rolling,were carried out on twin roll cast AZ31 alloy sheet to study the influence of strain path change on the evolution of the rolling microstructure and texture as well as the anisotropic properties of AZ31 alloy sheet with microscopy,X-ray diffraction technique and tensile tests.It is found that cross rolling gives rise to more uniform microstructure and stronger texture intensities compared with unidirectional rolling.The differences in the microstructure and texture intensities are reflected in the anisotropy characterized by the difference in the yield stress and the fracture elongation that were measured along directions in the rolling plane at angles of 0■,45■and 90■from the rolling direction.     

New Time-resolved-Tween 80 Chemiluminescent System for Simultaneous Determination of Trace Gold and Osmium

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Effect of fabrication parameters on the microstructure,in-plane anisotropy and magnetostriction of Fe-Ga thin films

The microstructure,in-plane anisotropy,and magnetic properties of Fe-Ga thin films were investigated by X-ray diffraction analysis,vibrating sample magnetometer,and capacitive cantilever method.The in-plane induced anisotropy is well formed by the applied magnetic field during sputtering,and the anisotropy field Hk decreases with the sputtering power increasing.The coercivity of Fe-Ga thin films decreases with increasing power when the sputtering power is less than 60 W and increases when the power is larger than 60 W.The magnetostriction of the thin films reaches 66 × 10-6 at the sputtering power of 60 W.Excellent Fe-Ga films,which exhibit good field sensitivity,low coercivity and high magnetostriction,have been fabricated at the power of 60 W,and they can be used as the materials of magnetostrictive transducers.     

均匀化退火对纯铝铸轧-冷轧板各向异性的影响

采用晶体取向分布函数（ODF）对织构进行检测及金相组织观察,研究不同的均匀化退火制度对纯铝铸轧一冷轧板材各向异性的影响。结果表明,对1100板材进行不同方案的均匀化退火,当均匀化退火制度为580℃／13h时,板材立方织构组分比例迅速下降,同时铜织构也有所下降,但散漫度较大,同时晶粒细小均匀,随机织构比例增大,制耳率低于2．5％,板材各向异性减小。均匀化退火制度主要通过改变板材织构组分、比例、晶粒度以及改变Fe和Si组织形态的变化等影响纯铝铸轧板材的各向异性。