对坦碳化物的异常硬度的洞察力来自位移动性的洞察力
Brennan R Watkins1, C Haas Blacksher2, Alyssa Stubbers3
1Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA. brenno@colostate.edu.
Nature communications
|December 5, 2024
概括
碳化物 (TaCx) 呈现异常硬度,原因是碳含量较低时滑动系统的转移. 脱位行为的这种变化解释了在批量样本中观察到的硬度峰值,但不是薄膜.
科学领域:
- 材料科学 材料科学 材料科学
- 固态物理 固态物理
- 物理化学 物理化学
背景情况:
- 碳化物 (TaCx) 显示异常硬化和软化与碳含量变化.
- 这种自1963年以来观察到的现象缺乏明确的解释.
- 以前使用弹性刚度的研究未能阐明异常硬度行为.
研究的目的:
- 确定碳化物异常硬度背后的主要机制.
- 调查滑动系统偏好在TaCx中的作用,作为碳含量的函数.
- 为了比较散装和薄膜TAC的硬度行为x.
主要方法:
- 通过结晶学分析研究了TaCx中的滑动系统偏好变化.
- 在散装和薄膜TaCx样本上进行实验硬度测量.
- 在不同碳度下分析了失位解离的能量有利性.
主要成果:
- 在TaCx中观察到从{111}B1到{110}B1的滑动系统偏好转变,碳含量下降.
- 这种滑动系统的变化被确定为TaCx异常硬度的主要驱动因素.
- 在散装TaCx中存在一个异常的硬度峰值,但由于位移可塑性有限,在纳米晶体薄膜中没有.
结论:
- 滑动系统偏好的转变是坦碳化物异常硬度的关键机制.
- 在碳含量较低的{111}B1平面上,Shockley部分解离的能量优势降低推动了这种过渡.
- 散装和薄膜碳化物之间的可塑性机制的差异解释了观察到的硬度行为变化.
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