相关实验视频
Updated: Dec 27, 2025

05:04
Determining the Mechanical Strength of Ultra-Fine-Grained Metals
Published on: November 22, 2021
2.5K
超细粒度金属的高压增强
Xiaoling Zhou1,2,3, Zongqiang Feng4, Linli Zhu5,6
1Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai, China.
Nature
|February 26, 2020
概括
霍尔-佩奇关系在15纳米以下破裂,导致软化. 这项研究表明的粒度持续增强至3纳米,通过联合硬化机制实现超高的强度.
科学领域:
- 材料科学
- 纳米技术
- 机械工程
背景情况:
- 霍尔 - 佩奇关系预测金属强度增加与粒度减少.
- 已知这种关系在临界颗粒大小 (10-15 nm) 以下分解,导致材料由于变形机制的改变而变软.
- 之前的抗软化方法包括稳定谷物边界.
研究的目的:
- 在高压下研究纯的机械行为,颗粒大小低至3nm.
- 要确定连续增强是否发生在极小的粒度,挑战已建立的霍尔-佩奇分解.
- 确定纳米晶体金属增强强度的基础强化机制.
主要方法:
- 在现场跟踪产量应力和变形纹理,使用与辐射X射线衍射相结合的钻石.
- 在纯样本上的高压实验,颗粒大小从200nm到3nm不等.
- 使用模拟和传输电子显微镜进行补充分析.
主要成果:
- 随着颗粒尺寸从200nm减少到3nm,在样本中观察到持续的强化.
- 在小于20nm的粒度下增强强度,与Hall-Petch关系的预期分解相反.
- 在3纳米粒度的中达到约4.2GPa的强度和10.2GPa的最大流量应力.
- 在黄金和样本中观察到类似的强化模式.
结论:
- 可以克服霍尔-佩奇关系,证明持续增强到3纳米的颗粒大小.
- 3纳米颗粒尺寸的超高强度是由于脱位硬化和颗粒边界可塑性的叠加而产生的.
- 这些发现为设计超强金属提供了途径,通过精确控制粒径和变形机制.
相关概念视频
Stress-Strain Diagram - Ductile Materials
1.8K
The stress-strain relationship in ductile materials such as structural steel or aluminium is intricate and progresses through several stages. When a specimen is loaded, it initially exhibits a linear length increase, depicted by a steep straight line on the stress-strain diagram. It indicates the material is elastically deforming and will return to its original shape once unloaded. However, when a critical stress value is reached, plastic deformation begins. This stage sees substantial...
1.8K
Residual Stresses
503
Residual stresses reside in a structure even after removing the original stress inducer. This phenomenon often arises from varied plastic deformations across different parts of a structure. Consider a rod stretched beyond its yield point. It will not regain its original length due to permanent deformation. Even after load removal, the rod does not entirely lose stress because of uneven plastic deformations, resulting in residual stresses. The computation of these stresses in structures is...
503
Stress Concentrations
557
Stress concentration is when stress intensifies near discontinuities such as holes or abrupt cross-sectional changes in a structural member. This localized stress can often surpass the average stress within the member. The stress distribution in flat bars, either with a circular hole or varying widths connected by fillets, can be determined experimentally using a photoelastic method. The results are based on ratios of geometric parameters like the ratio of the hole's radius to the smaller...
557
Yield Criteria for Ductile Materials under Plane Stress
423
In designing structural elements and machine parts using ductile materials, it is crucial to ensure that these components withstand applied stresses without yielding. Yielding is initially determined through a tensile test, which evaluates the material's response to uniaxial stress. However, tensile stress is insufficient when components face biaxial or plane stress conditions This condition requires advanced criteria to predict failure.
The Maximum Shearing Stress Criterion, also known as...
The Maximum Shearing Stress Criterion, also known as...
423
Hooke's Law
1.3K
Hooke's law, a pivotal principle in material science, establishes that the strain a material undergoes is directly proportional to the applied stress, defined by a factor called the modulus of elasticity or Young's modulus.
1.3K
Bonding in Metals
51.5K
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
51.5K

