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首页> 外文学位 >INVESTIGATION OF THE SURFACE DEFECT STRUCTURES ON SINGLE CRYSTALS OF MOLYBDENUM, NICKEL, AND BISMUTH INDUCED BY PULSED LASER IRRADIATION: CHARACTERIZATION BY LEED AND SINGLY POSITIVE HELIUM ION CHANNELING (THERMAL STRESS, SLIP, DISLOCATIONS).
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INVESTIGATION OF THE SURFACE DEFECT STRUCTURES ON SINGLE CRYSTALS OF MOLYBDENUM, NICKEL, AND BISMUTH INDUCED BY PULSED LASER IRRADIATION: CHARACTERIZATION BY LEED AND SINGLY POSITIVE HELIUM ION CHANNELING (THERMAL STRESS, SLIP, DISLOCATIONS).

机译：脉冲激光辐照诱发的钼，镍和铋单晶表面缺陷结构的研究：LEED和单正氦离子通道（热应力，滑动，位移）表征。

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摘要

The technique of LEED-Spot Profile Analysis (LEED-SPA) and He+ ion channeling have been used to investigate the response of molybdenum, nickel and bismuth single crystals to pulsed laser irradiation. Samples of molybdenum and nickel with (100) orientations were irradiated with a Q-switched, frequency doubled Nd:YAG laser under ultra-high vacuum conditions. Good epitaxial regrowth of the melted surfaces was indicated by the appearance of a well defined LEED pattern. Analysis of the spot profiles as a function of incident electron energy and annealing time at 1000 C indicates the initial formation of random island structures on the surface which coalesce toward a flat surface with prolonged heating. Samples which had been disordered in the near surface region by Ar+ ion bombardment exhibited a sharp LEED pattern after pulsed laser melting.; The (0001), (1010), and (2110) surfaces of bismuth were pulsed laser melted using a Q-switched Ruby laser. Channeling, Nomarski Interference Contrast Microscopy, and selective chemical etching indicate that the (0001) surface regrows epitaxially with no increase in disorder after pulsed laser melting at low laser fluences. Both the (1010) and (2110) surfaces show a marked increase in disorder after irradiation. The responses of these metals and the data are explained using a thermomechanical stress model in which the materials plastically deform in response to the high thermal gradients induced during pulsed laser irradiation.
机译：LEED-Spot Profile Analysis（LEED-SPA）和He +离子通道技术已用于研究钼，镍和铋单晶对脉冲激光辐照的响应。在超高真空条件下，用调Q倍频Nd：YAG激光辐照（100）取向的钼和镍样品。良好定义的LEED图案的出现表明熔融表面的外延性良好。根据入射电子能量和在1000℃下退火时间的函数对光斑轮廓进行分析，表明在表面上形成了随机的岛状结构，该结构在长时间加热下会聚结成平坦的表面。脉冲激光熔化后，在近表面区域被Ar +离子轰击扰乱的样品表现出清晰的LEED图案。铋的（0001），（1010）和（2110）表面使用调Q红宝石激光器进行脉冲激光熔化。通道，Nomarski干涉对比显微镜和选择性化学蚀刻表明，在低激光通量下脉冲激光熔化后，（0001）表面外延长大，无序增加。 （1010）和（2110）表面在辐照后均显示出明显的无序增加。使用热机械应力模型解释了这些金属和数据的响应，其中材料响应于在脉冲激光辐照期间引起的高热梯度而发生塑性变形。

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  • 作者

    HELMS, AUBREY LYNN, JR.;

  • 作者单位

    Princeton University.;

  • 授予单位 Princeton University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1986
  • 页码 228 p.
  • 总页数 228
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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