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911.
Yu-Kai Chen Chia-Ming Hsu Sinn-Wen Chen Chih-Ming Chen Yu-Chih Huang 《Metallurgical and Materials Transactions A》2012,43(10):3586-3595
Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys?? development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523?K, 1073?K, and 1273?K (250?°C, 800?°C, and 1000?°C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn3Co2Cu8, was found. The solubilities of Cu in the ??-CoSn3 and CoSn2 phases at 523?K (250?°C) are 4.2 and 1.6?at. pct, respectively, while the Cu solubility in the ??-Co3Sn2 phase is as high as 20.0?at. pct. The Cu solubility increases with temperature and is around 30.0?at. pct in the ??-Co3Sn2?at 1073?K (800?°C). The Co solubility in the ??-Cu6Sn5 phase is also significant and is 15.5?at. pct at 523?K (250?°C). 相似文献
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916.
Ching-Chien Huang Yung-Hsiung Hung Jen-Yung Hsu 《Journal of Materials Science: Materials in Electronics》2013,24(11):4411-4418
By using a new and simple blade casting method, a lighter, thinner and higher absorption property sintering NiCuZn ferrite electromagnetic wave absorber sheet was first demonstrated. The electromagnetic wave absorption ability was enhanced by sintered NiCuZn ferrite absorbent. The experiment results reveal that NiCuZn ferrite with thickness 0.1 mm absorber sheet achieves its maximum reflection loss value above 0.5 dB at 13.46 MHz. Meanwhile, the absorption bandwidth is larger than 1 MHz is profitable for wideband electromagnetic wave absorbing. The absorption properties could be controlled by the variation of Nickel content in the spinel lattice and the sintering temperature of NiCuZn ferrites. More homogenous microstructure of SEM micrograph and better crystalline XRD pattern may be responsible for the best absorption ability at 1,150 °C sintering temperature. The absorption properties were also successfully analyzed in this work, which took into account both the frequency at the reflection loss minimum (f r) shift correlated with the value of inductance (L) and impedance (Z) of sintered toroidal cores and the power reflection loss (Γ) depending on ε″, μ″, and $\sqrt {\varepsilon \mu }$ , where ε and μ are complex relative dielectric permittivity and permeability, respectively, for the attenuation material. The sintering NiCuZn ferrites could merit to be potential candidates as electromagnetic attenuation materials to meet the demands for miniaturization, broader relative bandwidths at HF (3–30 MHz) and beneficial for fabrication of radio frequency identification metal tag. 相似文献
917.
Hsiang-Chen Hsu Li-Ming Chu Wei-Yao Chang Yi-Feng Chen Jih-Hsin Chien Shen-Li Fu Shin-Pon Ju Wen-Jui Feng 《Journal of Materials Science: Materials in Electronics》2013,24(9):3594-3602
The objective of this research is to investigate the nanomechanical properties of ultra-thin Pd-coated copper (Cu) wire (ψ = 0.6 mil) and nanotribology along the interfacial between free air ball (FAB) and aluminum (Al) bond pad during wirebonding process. Two major analyses are conducted in the present paper. In the first, the characteristic of heat affected zone and FAB for Cu wire has been carefully experimental measured. Nanoscale interfacial tribology behavior between Cu FAB and Al pad is examined by atomic force microscopy. Secondary, the dynamic response on Al bond pad and beneath the pad during wirebonding process has been successfully predicted by finite element analysis. Micro-tensile mechanical properties of Cu wire before and after electric flame-off (EFO) process have been investigated by self-design pull test fixture. Experimental obtained hardening constant in Hall–Petch equation has significantly influence on the localize stressed area on Al pad. This would result in Al pad squeezing (large plastic deformation) around the smashed FAB during impact stage and the consequent thermosonic vibration stage. Microstructure of FAB is also carefully investigated by nanoindentation instruments. A real-time secondary EFO scheme has been conducted to reduce the strength of Cu wire and increase the bondability. All the measured data serve as material inputs for the finite element model based on explicit software ANSYS/LS-DYNA. In addition, nanoscale bondability on Cu-Al intermetallic compound is simulated by molecular dynamics. A series of comprehensive parametric studies were conducted in this research. 相似文献
918.
Hsueh-Chuan Hsu Shih-Kuang Hsu Hsi-Kai Tsou Shih-Ching Wu Tsung-Hsuan Lai Wen-Fu Ho 《Journal of materials science. Materials in medicine》2013,24(3):645-657
Porous titanium and titanium alloys are promising scaffolds for bone tissue engineering, since they have the potential to provide new bone tissue ingrowth abilities and low elastic modulus to match that of natural bone. In the present study, porous Ti–7.5Mo alloy scaffolds with various porosities from 30 to 75 % were successfully prepared through a space-holder sintering method. The yield strength and elastic modulus of a Ti–7.5Mo scaffold with a porosity of 50 % are 127 MPa and 4.2 GPa, respectively, being relatively comparable to the reported mechanical properties of natural bone. In addition, the porous Ti–7.5Mo alloy exhibited improved apatite-forming abilities after pretreatment (with NaOH or NaOH + water) and subsequent immersion in simulated body fluid (SBF) at 37 °C. After soaking in an SBF solution for 21 days, a dense apatite layer covered the inner and outer surfaces of the pretreated porous Ti–7.5Mo substrates, thereby providing favorable bioactive conditions for bone bonding and growth. The preliminary cell culturing result revealed that the porous Ti–7.5Mo alloy supported cell attachment. 相似文献
919.
Yu-Yun Chen Jin-Cherng Hsu Chun-Yi Lee Paul W. Wang 《Journal of Materials Science》2013,48(3):1225-1230
Aluminum doped zinc oxide (AZO) films were prepared at room temperature by ion beam co-sputtering system under various oxygen partial pressures. The structural, electrical, and optical properties of the films were studied by XRD, XPS, Hall measurement, and spectrometer. The AZO film with low resistivity, 7.8 × 10?4 Ω cm, and high transparency, ~80 %, was obtained at the optimum oxygen partial pressure of 1.3 × 10?4 Torr and the intense (002) diffraction peak was observed simultaneously. Different optical band gaps observed in the films prepared under various oxygen partial pressures are closely related to the carrier concentrations in the films. Three O1s components were applied to fit the XPS O1s spectra. They consist of adsorbed oxygen species, oxygen in O-Zn bonds surrounded by oxygen vacancies, and oxygen in the O-Zn bonds. Two components, Zn in Zn–O bonds and Zn with higher than +2 oxidation states, were used to fit Zn2p3/2 spectra. It was found that the increase of film’s resistivity which may result from the drops in the oxygen vacancy, Zn interstitial, carrier concentration, and grain size. No apparent transmission change of the film in the visible light region as a function of oxygen partial pressure was detected. 相似文献
920.
The current study uses mediated regression analysis and structural equation modelling to test the proposition that supply chain management practices mediate the relationship between operations capability and firm performance. Operations capability is defined in terms of a firm's new product design and development, total quality management and just-in-time capabilities. Results support the research model and also suggest the existence of a direct relationship between operations capability and performance. 相似文献