（001）-oriented FePt/Ag composite films for perpendicular recording

FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10 FePt perpendicular to the film plane. It was found that the development of (001) texture depended strongly on the thicknesses of FePt magnetic layer and Ag underlayer. The L10 ordered FePt(15 nm)/Ag(50 nm) with (001) orientation can be obtained. And the perpen-dicular coercivity of FePt(15 nm)/...     

Magnetron sputtering deposition of [FePt/Ag]n multilayers for perpendicular recording

[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on the structure and magnetic properties of the multilayers were investigated. It was found that the difference between in-plane and out-of-plane coercivities varied with an increase of inserted Ag layer thickness in the [FePt 2 nm/Ag x nm]10 multilayers. The ratio of out-of-plane coercivity to in-plane coercivity reached the maximum value with the Ag layer thickness of 5 nm, indicating that the Ag layer thickness plays an important role in obtaining perpendicular orientation. For the [FePt 2 nm/Ag 5 um]n multilayers, perpendicular orientation is also influenced by n. The maximum value of the ratio of out-of-plane coercivity to in-plane coercivity appeared when n was given as 8. It was found that the [FePt 2 nm/Ag 5 nm]8 had a high perpendicular coercivity of 520 kA/m and a low in-plane one of 88 kA/m, which shows a strong perpendicular anisotropy.     

Micromagnetic studies of perpendicular recording FePt media with controllable grain size distributions

A 3-dimensional (3D) micromagnetic model combined with Fast Fourier Transform (FFT) method was built up to study the writability in the L10 FePt perpendicular medium. The effects of controllable grain size distributions were studied by grain growth simulation. It is found that the cross-track-averaged magnetization changes little between the L10 FePt medium with uniform or non-uniform grain size distribution.     

Diffusion behavior of W in the WCu/Ni interface

In order to clarify the W diffusion behavior at the WCu/Ni interface, a WCu/Ni diffusion couple was prepared, and the phase structure and constituents of the diffusion layer were characterized by a scanning electron microscopy and transmission electron microscopy. Based on the experimental data, the interdiffusion coefficient was calculated. The diffusion behavior was also verified by the simulation according to the first principle method. The results show that a diffusion layer with the thickness of 1 μm, which is composed of Cu rich solid solution and W rich solid solution, is formed on the surface of W particles. The interdiffusion coefficient of W in the transitional layer is 3.381 × 10⁻¹⁵ cm²/s, which is much larger than that of W in Ni. This is in good agreement with the simulation result.     

Influence of interface morphology on dynamic behavior and energy dissipation of bi-material discs

To investigate the dynamic behavior and energy dissipation of the rock?concrete interface, dynamic splitting tests on bi-material discs were conducted by using the split Hopkinson pressure bar. The test results reveal that with the change of the interface inclination angles (θ), the influence of interface groove width on the bearing capacity of specimens also varies. When θ increases from 0° to 30°, the bearing capacity of the specimen increases first and then decreases with the rise of the interface groove width; the optimal groove width on the rock surface in this range of interface inclination angles is 5 mm. When θ increases from 45° to 90°, the bearing capacity of the specimen has no obvious change. Moreover, when θ increases from 0° to 45°, the dissipated energy of the specimens rises obviously at first and then tends to be stable as the width of the interface groove increases.     

Anomalous debonding behavior of a polymer/inorganic interface

Adhesion and subcritical debonding at the interface between a thin diglycidyl ether of bisphenol F polymer layer and either SiN_x or SiO₂ passivated silicon substrates are described. The interface is characterized by weak hydrogen bonding. Prolonged exposure to a moist environment resulted in a time-dependent decrease in adhesion. Subcritical debond-growth rates as a function of applied loads were sensitive to temperature and relative humidity, and greatly accelerated in the presence of cyclic loading. Of particular interest was the occurrence of an anomalous region of persistent debonding that developed below ∼10⁻⁸ m s⁻¹ under both monotonic and cyclic loading. In this region, debond-growth rates were characterized by a weak dependence on the applied loads, a strong dependence on moisture activity, and the absence of a measurable threshold below which debonding could not be measured. We propose a new stress-dependent transport model that describes the moisture diffusion mechanism responsible for this anomalous behavior.     

超声作用下Fe/Sn体系的润湿行为

采用润湿平衡法研究了超声波作用下熔融纯锡钎料在铁基板上的反应润湿性能. 通过测试锡铁体系的润湿力曲线,结合超声波的传播特性以及润湿后母材的微观形貌,对超声波作用下纯Sn钎料在母材铁片上润湿过程进行了详细描述,分析了超声波在润湿过程中起到的作用. 结果表明,在Sn/石英片润湿过程中附加超声波使得其润湿力增加. 在反应体系润湿力测试过程中附加超声波,能够减少钎料润湿母材的时间,增大钎料对母材的润湿力. 随着超声时间和超声功率的增加钎料润湿母材的时间减小,润湿力增大,固/液界面反应加剧,界面上生成了越来越厚、越来越致密的金属间化合物,使得母材表面相对于原始表面变得粗糙,从而润湿过程更容易进行,并且母材的表面张力的减小,使得润湿力增加.     

铁/铝爆炸复合双金属管界面的结合性能

采用爆炸焊接法制备Fe/Al双金属复合管,为表征复合管界面的结合性能进行了压缩、压扁及压剪实验。实验结果表明,复合管结合良好,其界面强度大于纯铝层的抗剪强度,并且能够承受轴向和径向变形。利用扫描电子显微镜观察了原始界面形貌。测试结果表明,结合良好的复合管界面呈波状或直线状。采用液压胀形工艺以Fe/Al双金属复合管制备出复合管正三通,发现良好的界面结合对铁/铝双金属管的塑性成型具有重要作用。     

Microstructure and interface fracture of LPPS Ni／Fe and Cu／Ni sprayed materials

The interfaces of two materials, Ni/Fe and Cu/Ni, deposited by low pressure plasma spraying method,were studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS). The adhesion between coatings and substrates was measured with the aid of Knoop interfacial indentation testing method. The results show that the interfacial micrcstructures have strong influence on the mechanical properties. Cu/Ni interface is weak link with NiO amorphousphase. Ni/Fehave strong in-interracial layer consists primarily of Fe and Ni oxide crystalline phases, containing dispersive (Fe, Ni) spotlike intermetaUic compound phase in nanometer dimension, and the interracial interdiffusion was detected. The micro-mechanism of interracial fracture was discussed.     

垂直晶界铜双晶的拉伸变形行为

利用数字图像相关法研究了垂直晶界铜双晶试样的拉伸变形行为,获得了拉伸过程中试样表面的全场变形分布。结果表明:试样整体变形呈"双颈缩"现象,试样表面的应变分布不均匀,晶界附近的应变水平低于晶粒内部的,试样总是在软取向的晶粒内首先发生塑性变形并断裂。借助扫描电镜(SEM)原位拉伸实验观察到在拉伸过程中滑移带不能穿过晶界。以上结果说明,铜双晶试样拉伸变形行为与组元晶粒的晶体取向和晶界的属性有关,软取向的晶粒更容易发生塑性变形,而大角度晶界在拉伸过程中具有强化效应,对晶粒的滑移变形有阻碍作用。     

Effects of donor concentration and oxygen partial pressure on interface morphology and grain growth behavior in SrTiO3

Change in interface morphology with ionic vacancy concentration and the correlation between interface structure and grain growth behavior in strontium titanate (SrTiO₃) have been investigated using SrTiO₃ single crystals and powder compacts. Under experimental conditions where SrTiO₃ contains a negligible amount of ionic vacancies, the shape of the single crystal embedded in matrix grains was well faceted, showing a strong anisotropy in interfacial energy. However, as strontium or oxygen vacancies increased with the addition of an Nb₂O₅ donor dopant or reduction of oxygen partial pressure, the faceted shape changed to a smoothly curved rough one indicating that an interface roughening transition occurred and, as a result, the anisotropy in interfacial energy was considerably reduced. Grain growth behavior was also strongly dependent on the interface structures; while normal grain growth occurred when the interfaces were rough, abnormal grain growth behavior was observed in the samples with faceted interfaces. It appears, therefore, that the ionic vacancies in SrTiO₃ can cause the interface roughening transition and change the resultant grain growth behavior.     

铜/锡界面间扩散行为分子动力学模拟

采用分子动力学方法,基于MEAM原子间作用势模型模拟了钎焊过程中固液界面扩散过程,从原子尺度对液态钎料原子向母材金属中的扩散行为进行模拟计算.计算了锡钎料在510 K温度下向母材中的扩散系数.结果表明,当扩散反应达到平衡态时,原子位移平均平方代换与反应时间成线性关系,钎料原子在x与y矢量方向扩散速度相近,且远大于z方向扩散速率.根据爱因斯坦扩散方程计算得到界面反应过程中钎料原子在xyz三个矢量方向上的扩散系数分别为2.03×10-9,2.05×10-9,5.06×10-10 cm2/s.z方向扩散系数模拟值同试验值比较,模拟结果与试验结果吻合一致.     

The magnetic properties and interface electronic structure for the epitaxial Fe/MgO/Fe(001) single crystal magnetic tunneling junctions

采用分子束外延技术在GaAs(001)-4×6衬底上外延出Fe/MgO/Fe(001) 单晶磁性隧道结。原位的表面磁光克尔效应（SMOKE）测量表明：当外磁场沿[1-10]方向时，隧道结的SMOKE回线具有典型的双矫顽力特性。下电极Fe层的矫顽力（~200 Oe）约是上电极Fe层矫顽力（~10 Oe）的20倍。矫顽力的增强主要被归结为MgO/Fe (001)界面对下电极铁磁层的钉扎作用。自旋分辩的光电子能谱测量表明，在MgO覆盖到Fe(001)表面后，Fe(001)费密面的自旋极化率P由负值转变为正值。P符号的改变被归结为MgO/Fe (001)界面电子自旋结构的改变。     

Role of the interface oxide film/alloy composition and stability of stainless steels

X‐ray photoelectron spectroscopy (XPS), a powerful method for investigating composition and thickness of thin films in the nanometer range, has been used to characterize the surface of two stainless steels with different bulk composition, DIN 1.4301 (18%Cr 8%Ni) and DIN 1.4529 (20%Cr 25%Ni 6%Mo) after mechanical polishing and after potentiostatic passivation in a wide range of potentials in sulfate solutions at different pHs. The XPS results confirm that the passive film thickness increases with applied potential, its composition is enriched in chromium oxy‐hydroxide after immersion in acidic solutions and polarization at low potentials whereas oxidized nickel is depleted. Special emphasis is given in this paper to the composition of the metal phase underneath the passive film. It is shown that the composition of the interface is strongly enriched in nickel for both stainless steels being 28 ± 2 wt% Ni versus a value of 8% in the bulk and 45 ± 2 wt% versus 25 wt%Ni in the bulk, respectively. The composition of the interface for a given alloy remains unchanged in a wide range of conditions of passive film formation such as pH, applied potential, passivation time. These results are discussed with respect to the influence of the interface composition on the corrosion rate of alloys in the passive state and on their pitting resistance.     

Mechanical properties and interface morphology of Mg/Al ultrasonic spot weld bonding welds

This paper investigates the mechanical properties and interface morphology of Mg/Al ultrasonic spot welding (USW) joint, adhesive bonding (AB) joint and ultrasonic spot weld bonding (USWB) joint. The peak load and fracture energy of USWB joint increased significantly compared to that of USW joint and AB joint. The USWB joint presented a hybrid fracture mode which was composed of the delamination failure at adhesive/Mg interface, cohesive failure within the adhesive and cleavage failure in the weld zone. The interface morphology suggested that USWB joint exhibited fewer defects in the cured adhesive matrix and elevated connection density of adhesive/metal interface, which improved joint strength and altered the fracture mode.     

Tunable perpendicular anisotropic magnetoresistance in CoO/Co/Pt heterostructures

Transport properties of magnetron-sputtered CoO/Co/Pt heterostructures were investigated by physical property measurement system.Different types of magnetoresistance are observed in the heterostructures,including isotropic anisotropic magnetoresistance(AMR),AMR with geometric size effect,and interfacial effect.A reversal in sign of perpendicular AMR is found in the film CoO(3 nm)/Co(3 nm)/Pt(3 nm) compared to the film CoO(3 nm)/Co(3 nm)/CoO(3 nm),which is associated with Pt.Moreover,perpendicula...     

Crystallography of Fe2Al5 phase at the interface between solid Fe and liquid Al

In this study, the microstructures and crystallographic features of a η-Fe₂Al₅ phase formed on pure Fe hot-dipped in a pure Al melt at 750 °C were examined in order to understand the η phase layer formation having a saw-tooth morphology. A number of the columnar η grains (forming the η phase layer) grow towards the solid Fe (α-Fe) side along the [001] direction, resulting in a significant saw-tooth morphology at the interface between the η and α-Fe phases. The neighboring η grains have high-angle boundaries with a common [001] axis. In the η phase layer, the low-angle boundaries develop close to the liquid Al side, and their density becomes higher with longer dipping times, resulting in the development of a fine dislocation substructure in the η phase. In the α-Fe phase, fine substructure consisting of a high density of low-angle boundaries develops around the growth tips of the columnar η grains. These substructure developments are likely responsible for the α → η transformation strain. A possible mechanism for the formation of this η phase layer having a saw-tooth morphology will be discussed in terms of the stress field caused by the α → η transformation.     

FePt/Au多层膜的结构和磁性能研究

采用磁控溅射在SiO2<0001>基片上制备了FePt(2nm)/Au(tnm)多层膜,将其在不同温度下进行热处理。利用X射线荧光光谱仪、X射线衍射仪、振动样品磁强计和原子力显微镜对样品的结构和性能进行了研究。结果表明,沉积态样品具有超晶格结构,fccFePt和Au共格生长。经过较低温度热处理后,样品仍然保持超晶格结构。样品经400℃热处理后,开始发生有序化转变。经600℃热处理后,平行于膜面和垂直于膜面的矫顽力分别为811.7和829.2kA·m-1。当t=2.5nm时,最有利于L10-FePt相的形成。在磁化过程中,畴壁移动和磁矩转动机制共存。样品经热处理后,形成了均匀的薄膜。     

高碳Nb-Ti-V系Fe基堆焊层中C/S界面结构

利用SEM和TEM观察、分析了高碳Nb-Ti-V系堆焊层中颗粒碳化物与固溶体基体间的界面(C/S界面)结构.表明:C/S界面洁净,两相间为直接的原子结合,错配度δ=6.1%～8.3%,界面位向关系为:(002)α-Fe//(220)(NbTiV)c;对MM200上的磨损试件观察亦表明,其C/S界面结合强度高,碳化物的脱落极少,堆焊层耐磨性超过美国的MG700.