 |
 |
 |
 |
 |
 |
||
 |
 |
 |
 |
 |
| 7 | 1/1 | 返回列表 |
| 查看: 2525 | 回復(fù): 6 | |||||
comma專家顧問 (知名作家)
材料人
|
[交流]
From www.imm.rwth-aachen.de: Grain Boundary Mechanics 已有6人參與
|
|
Grain Boundary Mechanics The reason for the multifarious use of metals and alloys as constructional or functional materials is founded by their outstanding properties. They are commonly used under conditions with high temperatures or mechanical strains for example in aerospace, energy industry or combustion engineering, which requires particular physical and mechanical properties to meet the necessary demands. The knowledge of the material's behaviour and the product life of a module is therefore the important issue. In fact, the properties of metal arise from their crystallinity. In this connection, construction faults at manufacturing have the most important impact on material, and not as may assumed the perfect periodic crystal build-up. Generally, the number, different kinds of crystal faults and their allocation is what we call Microstructure. If one can realize to influence the Microstructure in a purposeful way, it is possible to create new materials, for example gradient materials or composites. Additionally, materials, which already exist, e. g. nano crystal or high temperature components, can be improved and one is able to optimise the properties according to the purpose. Grain boundaries are one of the most important parts of Microstructure, being available in almost every crystal material. The only exception is build by a special cultured single crystal. Usually, grain boundaries arise by solidification of crystals. Macroscopically, they are interior interfaces of materials, in which place the crystallographic orientation changes in a discontinuously way. Hence, they are part of crystal solid bodies but with different properties to the rest of the crystal, having a direct impact on the mechanically and electronically characteristics of ones crystal. Especially, the capability of moving, dissolving or regenerating under suitable conditions leads to the fact, that grain boundaries are the most important structural lattice imperfections in crystal materials. The grain boundary movement depends on a great number of parameters. Two of them are temperature and stress which have the greatest bearing on the mobility, because they are responsible for activating the movement. That's why they are called the driving force. Particularly, high temperatures can make grain boundaries moving very quickly, so that their movement alters the Microstructure and properties of the material. Creating models, which simulate the grain boundary movement and describe the Microstructure development during a technical process, for example at deformation or recrystallisation, can help to control the changes of a material's properties and Microstructure development during the production process. Furthermore, these models deliver information about the behaviour of a certain module at its usage. Grain boundary engineering, in general, is the survey of grain boundary movement, which has become a very important part in research in recent time. It means that one is able to impact the behaviour of material and alter the Microstructure by activating grain boundary movements. Some materials, like gradient materials are defined different in various parts. So the knowledge of grain boundary movement helps to adjust them more precisely, getting a better calibration between the material and the requirements of its use. In recent years, there has been the presumption that grain boundary movements, which have been distinguished between mobile and immobile ones, are not impacted by mechanical strains. Material's behaviour under mechanical strain is not constrained by grain boundaries, except a non-mechanical grain boundary movement would be activated by high temperatures. Eventually, it is our aim to investigate, if grain boundaries are really independent from mechanical strains, and if they can be still distinguished between mobile and immobile ones. For this purpose, we produce so called bi-crystals with only one single grain boundary and try to activate the movement by a mechanical stress field. The result is that grain boundaries and their movements actually are able to impact by external fields which abandon most of the physical theories about interface dynamics. Even the distinction between mobile and immobile grain boundaries does not seem to be sensible any longer. For example, low-angle grain boundaries are supposed to be immobile, but actually, they are able to move much faster than mobile high-angled grain boundaries under appropriate conditions. In fact, there are several mechanisms with different parameters which are able to actuate a grain boundary movement, depending on the grain boundaries structure and their driving force. The knowledge of the different mechanisms of moving is quite important, cause we've done a step towards materials design by grain boundary engineering. Right now we're in the position to intervene in the kinetic of grain boundaries, while using the appropriate test conditions. |
回復(fù)此樓» 猜你喜歡
本科鄭州大學(xué)物理學(xué)院，一志愿華科070200學(xué)碩，346求調(diào)劑
已經(jīng)有3人回復(fù)
-
能源材料化學(xué)課題組招收碩士研究生8-10名
已經(jīng)有11人回復(fù)
-
求材料調(diào)劑
已經(jīng)有9人回復(fù)
-
材料專碩英一數(shù)二306
已經(jīng)有5人回復(fù)
-
085600材料與化工調(diào)劑 324分
已經(jīng)有9人回復(fù)
-
0703化學(xué)調(diào)劑
已經(jīng)有12人回復(fù)
-
0703化學(xué) 305求調(diào)劑
已經(jīng)有4人回復(fù)
-
0703化學(xué)調(diào)劑，求各位老師收留
已經(jīng)有10人回復(fù)
-
271材料工程求調(diào)劑
已經(jīng)有5人回復(fù)
-
281求調(diào)劑（0805）
已經(jīng)有16人回復(fù)
» 本主題相關(guān)價值貼推薦，對您同樣有幫助:
- Theoretical Concepts of Quantum Mechanics [Kindle Edition]
已經(jīng)有29人回復(fù)
  |
2樓2011-05-16 22:14:59
csuboyle
木蟲 (正式寫手)
- 應(yīng)助: 16 (小學(xué)生)
- 金幣: 4137.6
- 紅花: 2
- 帖子: 917
- 在線: 242.7小時
- 蟲號: 278373
- 注冊: 2006-09-10
- 性別: GG
- 專業(yè): 金屬結(jié)構(gòu)材料
3樓2011-05-20 00:21:59
jwfu
至尊木蟲 (文壇精英)
- 應(yīng)助: 17 (小學(xué)生)
- 金幣: 21031.8
- 散金: 81
- 紅花: 21
- 沙發(fā): 3
- 帖子: 12262
- 在線: 911.8小時
- 蟲號: 680446
- 注冊: 2008-12-23
- 性別: GG
- 專業(yè): 金屬材料的合金相、相變及
4樓2011-06-04 12:07:54
蘭若寺僧
木蟲 (正式寫手)
- 應(yīng)助: 2 (幼兒園)
- 貴賓: 0.05
- 金幣: 4982.5
- 散金: 24
- 紅花: 4
- 帖子: 874
- 在線: 238.3小時
- 蟲號: 593066
- 注冊: 2008-09-05
- 專業(yè): 金屬材料的合金相、相變及
5樓2012-04-25 21:48:50
f090201102
木蟲 (正式寫手)
- 應(yīng)助: 12 (小學(xué)生)
- 金幣: 3905.1
- 散金: 322
- 紅花: 12
- 帖子: 774
- 在線: 588.4小時
- 蟲號: 3272039
- 注冊: 2014-06-13
- 性別: GG
- 專業(yè): 機械工程
6樓2016-11-29 22:44:09
wang_sylvie
金蟲 (著名寫手)
- 應(yīng)助: 8 (幼兒園)
- 金幣: 7321.8
- 散金: 456
- 紅花: 11
- 帖子: 1168
- 在線: 190.5小時
- 蟲號: 3575339
- 注冊: 2014-12-03
- 專業(yè): 金屬材料的微觀結(jié)構(gòu)
7樓2016-11-30 00:03:06
相關(guān)版塊跳轉(zhuǎn)
我要訂閱樓主 comma 的主題更新
| 7 | 1/1 | 返回列表 |
| 最具人氣熱帖推薦 [查看全部] | 作者 | 回/看 | 最后發(fā)表 | |
|---|---|---|---|---|
|
[考研] 311求調(diào)劑 +4 | 冬十三 2026-03-18 | 4/200 |
|
|---|---|---|---|---|
|
|
[考研] 26調(diào)劑/材料/英一數(shù)二/總分289/已過A區(qū)線 +7 | 步川酷紫123 2026-03-13 | 7/350 |
|
|
|
[考研] 311求調(diào)劑 +6 | 26研0 2026-03-15 | 6/300 |
|
|
[考研] 收復(fù)試調(diào)劑生 +4 | 雨后秋荷 2026-03-18 | 4/200 |
|
|
|
[考研] 304求調(diào)劑 +12 | 小熊joy 2026-03-14 | 13/650 |
|
|
|
[考研] 工科材料085601 279求調(diào)劑 +6 | 困于星晨 2026-03-17 | 6/300 |
|
|
|
[考研] 307求調(diào)劑 +3 | 冷笙123 2026-03-17 | 3/150 |
|
|
|
[考研] 0703化學(xué)336分求調(diào)劑 +6 | zbzihdhd 2026-03-15 | 7/350 |
|
|
|
[考研] 265求調(diào)劑 +3 | 梁梁校校 2026-03-17 | 3/150 |
|
|
|
[考研] 268求調(diào)劑 +6 | 簡單點0 2026-03-17 | 6/300 |
|
|
|
[考研] 301求調(diào)劑 +9 | yy要上岸呀 2026-03-17 | 9/450 |
|
|
|
[考博] 26博士申請 +3 | 1042136743 2026-03-17 | 3/150 |
|
|
|
[考研] 296求調(diào)劑 +5 | 大口吃飯 身體健 2026-03-13 | 5/250 |
|
|
|
[考研] 考研化學(xué)學(xué)碩調(diào)劑，一志愿985 +4 | 張vvvv 2026-03-15 | 6/300 |
|
|
|
[考研] 0854控制工程 359求調(diào)劑 可跨專業(yè) +3 | 626776879 2026-03-14 | 9/450 |
|
|
|
[考研] 085600材料與化工 求調(diào)劑 +13 | enenenhui 2026-03-13 | 14/700 |
|
|
|
[考研] 070305求調(diào)劑 +3 | mlpqaz03 2026-03-14 | 4/200 |
|
|
|
[考研] 308 085701 四六級已過求調(diào)劑 +7 | 溫喬喬喬喬 2026-03-12 | 14/700 |
|
|
|
[考研] 329求調(diào)劑 +3 | miaodesi 2026-03-12 | 4/200 |
|
|
|
[考研] 290求調(diào)劑 +7 | ADT 2026-03-12 | 7/350 |
|