一种相变材料的增强可逆性和不寻常的微观结构
Yintao Song1, Xian Chen, Vivekanand Dabade
1Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Nature
|October 5, 2013
概括
研究人员发现了Zn45Au30Cu25,一种新型的马氏体材料,具有特殊的可逆性. 这种材料在16,000个循环中表现出最小的转换温度变化和低歇斯底里,在可靠的应用中优于传统合金.
科学领域:
- 材料科学 材料科学 材料科学
- 固态物理 固态物理
- 晶体学 晶体学是指结晶学.
背景情况:
- 可逆的固体-固体马氏体相转换对于医疗传感器和能量转换设备等先进应用至关重要.
- 高可逆性,以低歇斯底里和在热循环下稳定的转换温度为特征,对于材料耐用性至关重要.
- 已经提出了理论上的"辅助因素条件",以提高材料的可逆性,超出现有的几何兼容性标准.
研究的目的:
- 为了研究一种新的马氏体材料Zn45Au30Cu25的可逆性和微观结构,该材料旨在满足理论辅因子条件.
- 为了比较Zn45Au30Cu25在转化稳定性和歇斯底里斯方面与像NiTi这样的既有合金的性能.
- 描述在相变循环过程中独特的微观结构特征及其与宏观性质的关系.
主要方法:
- 合成和描述Zn45Au30Cu25合金的情况.
- 进行了广泛的热循环实验,以评估转换温度稳定性和歇斯底里.
- 使用显微镜技术进行微结构分析,观察马石阶段.
- 实验结果与基于辅因子条件的理论预测进行比较.
主要成果:
- Zn45Au30Cu25表现出了显著的稳定性,在超过16000个循环后,转变温度的变化不到0.5°C,与NiTi的20°C变化形成鲜明对比.
- 该材料呈现出约2°C的低歇斯底里,明显低于NiTi高达70°C的歇斯底里.
- 观察到一种不寻常的"河流"马石微观结构,在循环过程中动态变化,同时保持可复制的宏观性质.
- 该材料密切满足了拟议的辅因子条件,与其增强的可逆性相关.
结论:
- Zn45Au30Cu25是第一个符合辅因子条件的马氏体材料,导致前所未有的可逆性.
- 这些发现验证了理论辅因子条件作为设计超可靠的马氏体材料的有希望的策略.
- 独特的,动态演变的微观结构与稳定的宏观性质相结合,为马氏体相变和材料设计提供了新的见解.
相关概念视频
Phase Transitions
22.3K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
22.3K
Phase Contrast and Differential Interference Contrast Microscopy
11.9K
Phase-Contrast Microscopes
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
11.9K
Phase Transitions: Sublimation and Deposition
19.6K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
19.6K
Phase Changes
5.2K
Phase transitions play an important theoretical and practical role in the study of heat flow. In melting or fusion, a solid turns into a liquid; the opposite process is freezing. In evaporation, a liquid turns into a gas; the opposite process is condensation.
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
5.2K
Phase Transitions: Melting and Freezing
14.5K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
14.5K
Polymer Classification: Crystallinity
3.7K
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
3.7K


