Fabrication of RGO/Cu composites based on electrostatic adsorption

To address the issues of reduced graphene oxide (RGO) dispersion in copper (Cu) matrix and interface bonding between RGO and Cu, an electrostatic adsorption method with interface transition phase design was employed to prepare the RGO/Cu based composites. Cu-Ti alloy powder was employed to improve the combination by forming carbides at the RGO-Cu interface. It was noted that the mechanical property of 0.3wt.%RGO/Cu-Ti composite was increased by 60% compared with that of the matrix. Strengthening mechanism analysis suggested that the enhancement of the mechanical property was ascribed to the load transfer and second phase strengthening which were from the improved dispersion of RGO and the in-situ formed titanium carbide phase.     

Microstructural evolution during reactive spray forming of dispersion strengthened Cu alloy

Dispersion strengthened Cu alloy was fabricated by injecting Cu-B alloy powders into the spray of Cu-Ti droplets. The microstructures of over-sprayed powders and spray deposited billet were observed by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The over-sprayed powders were composed of not only Cu-B and Cu-Ti alloy powders but also small amounts of Cu-B alloy powders surrounded by Cu-Ti droplets. Fine dispersoids of TiB were observed in the Cu-B powders surrounded by Cu-Ti, indicating that very rapid reaction of Ti and B had occurred during the flight of the droplets. TiB dispersoids of ∼10 nm having an orientational relationship with the Cu matrix were distributed in the Cu-B alloy powder region and coarser TiB dispersoids of ∼50 nm were observed in the circumferencial Cu-Ti region. The spray deposited billet consisted of the regions showing a fine microstructure of round shape, presumably originating from the injected Cu-B alloy powders, and a relatively coarse cellular microstructure. TiB2 and TiB of ∼200 nm were observed along the grain and cell boundaries. Fine TiB dispersoids of ∼10 nm having an orientational relationship with the Cu matrix were observed in both regions. The solidification behavior, with special interest in (he formation of dispersoids, was examined based on this observation.     

以Cu-Ti复合渗镀为先导的Si3N4陶瓷/金属钎焊连接

提出一种陶瓷表面多元离子复合渗镀合金化方法,采用该方法对Si3N4陶瓷表面进行Cu-Ti复合渗镀,然后在复合渗镀真空设备中进行渗镀Cu-Ti的Si3N4陶瓷与金属的钎焊.对Si3N4陶瓷表面的Cu-Ti渗镀合金层进行了EDS、XRD、SEM、OM测试分析和声发射划痕试验.结果表明,渗镀层中含有Cu、Ti、Fe、Si及Al元素,Cu、Ti分布比较均匀,渗镀合金层由Cu、CuTi2、TiSi2组成;声发射划痕试验结果表明,在100 N的最大载荷下,渗镀合金层与陶瓷基体未发生剥离和崩落现象.在100倍的光学显微镜及5000倍的电子显微镜下,钎焊接头中陶瓷/金属界面接合良好,无明显的宏观和微观缺陷.可在较低的真空度下实现陶瓷/金属钎焊,为陶瓷/金属钎焊连接提供了一个新方法.     

含H_2O气氛下Cu液中Ti的氧化SCIEI

本文研究了1500℃H_2O气氛下液态Cu合金中Ti的氧化。     

A THERMODYNAMIC INVESTIGATION ON SPINODAL DECOMPOSITION BOUNDARY IN Cu－Ti ALLOYS

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Effect of Annealing Ambient on the Self-Formation Mechanism of Diffusion Barrier Layers Used in Cu(Ti) Interconnects

Copper (titanium) [Cu(Ti)] films with low titanium (Ti) concentration were found to form thin Ti-rich barrier layers at the film/substrate interfaces after annealing, which is referred to as self-formation of the barrier layers. This Cu(Ti) alloy was one of the best candidates for interconnect materials used in next-generation ultra-large-scale integrated (ULSI) devices that require both very thin barrier layers and low-resistance interconnects. In the present paper, in order to investigate the influences of annealing ambient on resistivity and microstructure of the Cu alloys, the Cu(7.3at.%Ti) films were prepared on the SiO₂ substrates and annealed at 500°C in ultra-high vacuum (UHV) or argon (Ar) with a small amount of impurity oxygen. After annealing the film at 500°C in UHV, the resistivity was not reduced below 16 μΩ-cm. Intermetallic compounds of Cu₄Ti were observed to form in the films and believed to cause the high resistivity. However, after subsequently annealing in Ar, these compounds were found to decompose to form surface TiO _x and interfacial barrier layers, and the resistivity was reduced to 3.0 μΩ-cm. The present experiment suggested that oxygen reactive to titanium during annealing played an important role for both self-formation of the interfacial barrier layers and reduction of the interconnect resistivity.     

ZrO2陶瓷表面Cu-Ti复合渗镀研究

应用加弧辉光复合渗镀技术和自制Cu-Ti二元金属复合靶,对ZrO2陶瓷表面进行Cu-Ti复合渗镀。采用X射线能量色散谱分析（EDS）、扫描电子显微镜（SEM）面扫描、X射线衍射（XRD）、声发射划痕等试验方法对渗镀层的元素组成、成分分布、相组成、界面结合强度进行分析测试。结果表明渗镀层中存在Cu、Ti及Fe元素,各组分分布较为均匀,没有明显的成分偏聚现象;渗镀层由Cu2Ti、Cu2Ti4O、Ti8O15组成;渗镀层与陶瓷基体结合良好,在100 N最大载荷下未出现剥离和崩落现象。     

First-principles calculations on structural energetics of Cu-Ti binary system intermetallic compounds in Ag-Cu-Ti and Cu-Ni-Ti active filler metals

Structural, mechanical and thermodynamic properties, as well as the electronic structures of Cu-Ti binary system intermetallic compounds in Ag-Cu-Ti and Cu-Ni-Ti active filler metals were calculated systematically using a first-principles density functional theory (DFT). The calculated formation enthalpy index that all the Cu-Ti intermetallic compounds are thermodynamic stable from degradation to pure metals and the relationship between Cu content (x) and formation enthalpy (y) for tetragonal structure meets the function y=0.572+(−1.005/(0.048*sqrt(3.142/2)))*exp(−0.5*((x−47.167)/13.533)^2). The mechanical properties, including bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio v, and elastic anisotropy were derived from the elastic data C_ij. For the tetragonal Cu-Ti intermetallic compounds, the shear modulus G and Young's modulus E are negatively related to the formation enthalpy, while for the orthorhombic Cu-Ti intermetallic compounds, G and E are positively related to the formation enthalpy. Moreover, the elastic anisotropy increases in the following order: Cu₄Ti<CuTi₃<Cu₄Ti₃<Cu₂Ti<CuTi<CuTi₂<Cu₃Ti₂. The thermodynamic properties were estimated from the electronic structures and elastic constants simultaneously, and the results found that Cu₄Ti possess the best thermal conductivity and heat capacity among all the Cu-Ti intermetallic compounds, while CuTi₃ shows the worst ones. Finally, the relationship between electronic structures and physical properties was discussed, and get the inference that for the Cu-Ti intermetallic compounds, the mechanical properties are positively related to the strength of the covalent bond, while the thermophysical properties are influenced by the ionic character and covalent character simultaneously and the ionic character shows the dominant role, therefore, CuTi and Cu₄Ti₃ show the strongest mechanical properties due to the strongest covalent character, while Cu₄Ti shows the strongest thermal conductivity and heat capacity due to the strongest ionic character.     

TRANSFER OF Ti AND Si BETWEEN SLAGS AND MOLTEN Cu UNDER CONSTANT OXYGEN POTENTIAL

An experimental study has been made of the mass transfer of Ti and Si between slags and mol-ten Cu under constant oxygen potential at 1500℃.Apparent mass transfer coefficients of Tiand Si in molten Cu have been obtained.     

SIDEBANDS OF X-RAY DIFFRACTION IN AGE-HARDENED Cu-Ti ALLOY

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