Control of dislocation configuration in sapphire
Control of dislocation configuration in sapphire
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DOI：
10.1016/j.actamat.2004.10.002
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发表时间：
2005-01
期刊：
影响因子：
9.4
通讯作者：
A. Nakamura;K. Lagerlöf;K. Matsunaga;Jun'ichi Tohma;Takahisa Yamamoto;Y. Ikuhara
中科院分区：
文献类型：
--
作者：
A. Nakamura;K. Lagerlöf;K. Matsunaga;Jun'ichi Tohma;Takahisa Yamamoto;Y. Ikuhara
提出了一种利用“两阶段变形”技术和薄板热处理技术在蓝宝石中引入高密度单向位错的方法。蓝宝石晶体在1400℃基底滑移变形后，在1200℃进行第二阶段变形。结果发现，在1200°C的变形试验中，在采用两阶段变形技术变形的晶体中没有观察到通常在变形试验中观察到的孪晶和裂纹，并且获得了高达1.1×109/cm2的位错密度。这是因为在1400℃时产生的滑移位错在1200℃时的附加变形中促进了滑移超越孪晶。随后，将含有高密度位错的薄板在1400℃下退火30 min。结果发现，薄板上的位错能够在两个相对的表面上被拉直。这被认为是由于大的像力作用于位错由于自由表面。
A method to introduce high density of unidirectional dislocations in sapphire by a “two-stage deformation” technique and a heat-treatment of thin plate is proposed. After deformation of sapphire crystals by basal slip at 1400 °C, the samples were further deformed at 1200 °C as a second stage. It was found that twinning and cracking normally observed during deformation tests at 1200 °C were not observed in the crystals deformed using the two-stage deformation technique, and dislocation densities as high as 1.1×109/cm2were obtained. This is because the glide dislocations generated at 1400 °C promoted slip over twinning in the additional deformation at 1200 °C. Subsequently, thin plates containing the high density of dislocations were annealed at 1400 °C for 30 min. As a result, it was found that dislocations in the thin plate were able to be straightened across its two opposite surfaces. This is believed to be due to the large image forces acting on the dislocations due to the free surface.