不寻常的塑料应变诱导的相变现象在中
Sorb Yesudhas1, Valery I Levitas2,3,4, Feng Lin5
1Department of Aerospace Engineering, Iowa State University, Ames, Iowa, USA. sorbya@iastate.edu.
Nature communications
|August 15, 2024
概括
塑料应变,而不是压力,驱动着 (Si) 的相变. 这项研究揭示了局部应变诱导的相变,显示了较低的启动压力和新相共存,具有材料合成和表面处理中的应用.
科学领域:
- 材料科学 材料科学 材料科学
- 固态物理 固态物理
- 纳米技术纳米技术
背景情况:
- (Si) 是一种重要的电子材料.
- 在Si中,压力诱导的相变换 (PTs) 已经得到了充分的记录.
- 在Si的应变诱导PTs尚未在现场进行研究.
研究的目的:
- 在现场研究中的塑料应变诱导的相变.
- 为了探索粒子大小,屈服强度和压力之间的相关性,应变诱导的PT.
- 了解中应变诱导的PTs的机制和应用.
主要方法:
- 在现场观察塑料应变诱导的相变.
- 理论预测和实验证实了霍尔-佩奇效应对应变诱导的PT的影响.
- 在不同压力下进行压缩,剪切和扭转的应用.
主要成果:
- 应变诱导的Si-I→Si-II PT在压缩/剪切下开始于0.3 GPa,在水静压下明显低于16.2 GPa.
- 在应变下,Si-I→Si-III PT 在0.6 GPa开始,在水静压下没有观察到.
- 在扭转下观察到多个相 (Si-I,II,III,XI) 的并存,在环境压力下保留Si-II和Si-III.
结论:
- 塑料应变是Si相转换的更有效的驱动因素,而不是水静压.
- 一个基于堆积的脱位机制解释了观察到的现象.
- 这些发现为合成纳米结构材料和先进的表面处理提供了新的途径.
相关概念视频
Plastic Behavior
193
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and...
193
Transformation of Plane Strain
159
When analyzing elongated structures like bars subjected to uniformly distributed loads, it is essential to understand the transformation of plane strain when coordinate axes are rotated. This transformation helps to assess how material deformation characteristics vary with orientation, which is crucial in materials science and structural engineering.
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
159
Plastic Deformations
84
It is essential to understand how structural members behave under plastic deformation when the bending stress exceeds the material's yield strength. This state of deformation permanently alters the shape of the member, in contrast to the linear elastic behavior observed before yielding. The strain at any point in the member is expressed in terms of maximum strain. Notably, the neutral axis, which coincides with the centroid during elastic bending, shifts away from the centroid under plastic...
84
Plasticity
2.1K
Plasticity is the property where an object loses its elasticity and undergoes irreversible deformation, even after the deformation forces are eliminated. If a material deforms irreversibly without increasing stress or load, then this is called ideal plasticity. For example, when a force is applied to an aluminum rod, it changes its shape, but it does not return to its original shape once the force is removed. Plastic deformation or ductility is thus a permanent deformation or change in the...
2.1K
Thermal Strain
808
Thermal strain is a concept that arises when we consider how temperature changes affect structures. Unlike the conventional assumption that structures remain constant under load, real-world scenarios often involve temperature fluctuations that can significantly impact these structures. Consider a homogeneous rod with a uniform cross-section resting freely on a flat horizontal surface. If the rod's temperature increases, the rod elongates. This elongation is proportional to the temperature...
808


