• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Materials Science and Engineering >Understanding the role of Ca segregation on thermal stability, electrical resistivity and mechanical strength of nanostructured aluminum
【24h】

Understanding the role of Ca segregation on thermal stability, electrical resistivity and mechanical strength of nanostructured aluminum

机译：了解Ca偏析对纳米结构铝的热稳定性，电阻率和机械强度的作用

获取原文
获取原文并翻译 | 示例
       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Achieving a combination of high mechanical strength and high electrical conductivity in low-weight Al alloys requires a full understanding of the relationships between nanoscaled features and physical properties. Grain boundary strengthening through grain size reduction offers some interesting possibilities but is limited by thermal stability issues. Zener pinning by stable nanoscaled particles or grain boundary segregation are well-known strategies for stabilizing grain boundaries. In this study, the Al-Ca system has been selected to investigate the way segregation affects the combination of mechanical strength and electrical resistivity. For this purpose, an Al-Ca composite material was severely deformed by high-pressure torsion to achieve a nanoscaled structure with a mean grain size of only 25 nm. X-ray diffraction, transmission electron microscopy and atom probe tomography data revealed that the fcc Ca phase was dissolved for large levels of plastic deformation leading mainly to Ca segregations along crystalline defects. The resulting microhardness of about 300 HV is much higher than predictions based on Hall and Petch Law and is attributed to limited grain boundary mediated plasticity due to Ca segregation. The electrical resistivity is also much higher than that expected for nanostructured Al. The main contribution comes from Ca segregations that lead to a fraction of electrons reflected or trapped by grain boundaries twice larger than in pure Al. The two-phase state was investigated by in-situ and ex-situ microscopy after annealing at 200 °C for 30 min, where precipitation of nanoscaled Al_4Ca particles occurred and the mean grain size reached 35 nm. Annealing also significantly decreased electrical resistivity, but it remained much higher than that of nanostructured pure Al, due to Al/Al_4Ca interfaces that reflect or trap more than 85% of electrons.
机译：在低重量铝合金中实现高机械强度和高电导率的组合需要全面了解纳米级特征和物理性质之间的关系。通过晶粒尺寸减少强化强化提供了一些有趣的可能性，但受到热稳定性问题的限制。通过稳定的纳米级颗粒或晶界偏析的齐纳钉扎是稳定晶界的众所周知的策略。在本研究中，已经选择了Al-Ca系统以研究分离影响机械强度和电阻率的组合的方式。为此目的，通过高压扭转严重地变形Al-Ca复合材料，以实现纳米级结构，其平均晶粒尺寸仅为25nm。 X射线衍射，透射电子显微镜和原子探测断层扫描数据显示，FCC Ca相溶解在大量的塑性变形，主要用于沿着晶体缺陷的Ca偏析。得到的显微硬度约为300HV基于霍尔和PACCH法律的预测远高于预测，并且由于Ca偏析引起的晶界介导的塑性有限。电阻率也远高于纳米结构Al期望的电阻率。主要贡献来自CA偏析，其导致晶界反射或捕获的一部分，两倍于纯Al。通过原位和在200℃下退火30分钟的原位和前原位显微镜研究了两相状态，其中发生纳米级Al_4Ca颗粒的沉淀，平均晶粒尺寸达到35nm。退火也显着降低电阻率，但由于Al / Al_4CA界面，其仍然远高于纳米结构纯Al的型，其反射或捕获超过85％的电子。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号