Papers by Keyword: Two-Step Annealing

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Authors: Zheng Rong Zhang, Kazuyoshi Sekine
Abstract: In order to obtain a sharply cube textured silver sheet as the substrate for high temperature superconductor (HTS) film with high Jc (critical current density), warm rolling combined with two step annealing treatment has been performed to clarify the perspective of texture formation in pure silver. Two kinds of starting material, which are silver ingots of commercial purity obtained by casting in air and vacuum, were used to examine the effect of oxygen on texture development. The main feature of warm rolling texture obtained in this study was a strong Brass {011}<211> component with minor S {123}<412> component, and in some cases, cube {001}<100> component or Copper {112}<111> component appeared also depending on the warm rolling procedures. Upon crystallization, {001}<100>, {124}<4,12,7> and {13,6,15}<365> orientations were formed as the dominant components in silver sheets and the relative amount of their orientation components depended on the concrete annealing conditions applied and on the oxygen content. A very sharp single-crystal like cube texture has been successfully realized in the specimen, which was cast in vacuum, warm rolled by 95 percent and subsequently annealed as 1500C×10 min-5000C×30 min in nitrogen. Finally, we discussed the technological basis on sharp cube texture formation in f.c.c. pure metals with low stacking fault energy.
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Authors: Qiang Song, Shu Qing Qin
Abstract: In the present paper, the effects of two-step annealing on the soft magnetic properties of nanocrystalline Fe73.5Cu1Nb3Si13.5B9 melt spun ribbons were studied. The two-step annealing comprises low-temperature preannealing (first step) for an α-Fe(Si) phase nucleation in an amorphous matrix, and a subsequent high-temperature annealing (second step) for the growth of precipitated crystallites. Compared with a nanocrystalline alloy obtained by conventional one-step annealing at 550 °C for 1 h, the grain size of α-Fe(Si)crystalline phase in the Fe73.5Cu1Nb3Si13.5B9 alloy decreased greatly after it is pre-annealed at 480°C for 1 h followed by annealing at 550°C for 40 min. It has been shown that the soft magnetic properties can be significantly improved by applying two-step annealing. The decrease of grain size of α-Fe(Si) crystalline phase may result from the nucleation rate increase during the crystallization of pre-annealed.
353
Authors: Xiao Lei Qu, Jing Jin, Wei Min Shi, Yu Feng Qiu, Lu Huang, Ping Sheng Zhou, Wen Yun Dai
Abstract: A viscous Nickel (Ni) solution was applied on amorphous Si films by spin coating and its effect on the crystallization of amorphous Si films was investigated with a two-step annealing process. The experimental results show that with the help of the two-step annealing, the crystallization of the film can take place at 500oC. At the same time, the crystalline fraction gets up to 79.4% after annealing at a high temperature of 520oC and the grain size of the polycrystalline Si films is approximately 200 nm.
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Authors: Jing Jin, Xiao Lei Qu, Wei Min Shi
Abstract: Solution-based nickel (Ni)-induced crystallization (S-MIC) of amorphous silicon (a-Si) films has been studied with a two-step annealing process. We especially introduced Ethyl cellulose (EC) into the Ni-salt solution, so the viscous Ni-salt solution can be uniformly spin-coated on the a-Si film prepared by plasma enhanced chemical vapor deposition (PECVD). The annealing temperature can be first set from room temperature (RT) to 400°C and kept at 400°C for 2 h in nitrogen ambience. And then, it is increased from 500°C to 550°C and kept for several hours in the following annealing. The correlations among crystallization, the concentrations of Ni-salt solution and annealing conditions can be discussed. The experimental results show that with the help of the two-step annealing, the a-Si films can be crystallized at a low temperature of 500°C. The crystalline fraction gets up to 81.2% after annealing at 520°C for 2 h and the grain size of the polycrystalline Si film is approximately 0.2 μm. Energy dispersive spectroscopy (EDS) analysis shows that very little Ni metal atoms reside in the crystallized Si film for S-MIC.
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