| 查看: 352 | 回复: 1 | |||
| 当前主题已经存档。 | |||
liurenci金虫 (正式写手)
|
[交流]
［学术交流］橡树岭国家实验室关于intermetallic的描述
|
||
|
我见了一个高温合金群，欢迎高温合金以及金属间化合物的研究工作者加入。 群号：26820756 Intermetallic compounds are a unique class of materials, consisting of ordered alloy phases formed between two or more metallic elements where the different atomic species occupy specific sites in the crystal lattice (NRC, 1984; Anton et al., 1989). Intermetallics differ from conventional alloys in that they generally possess long-range-ordered crystal structures at ambient and intermediate temperatures. Intermetallic compounds form in composition ranges close to stoichiometric ratios. Thus, although the laws of chemical valency are usually not followed, the compounds often have relatively simple chemical names like TiAl, Ti3Al, NiAl, Ni3Al, CuZn, Cu3Au, and Nb5Si3. Intermetallics have characteristics of both metals and ceramics, and their mechanical properties are intermediate between metals (which are generally softer and more ductile) and ceramics (which are generally harder and more brittle). The predominant bonding in ceramics is covalent and ionic, as opposed to metallic bonding. Intermetallics contain both metallic and covalent bonds, depending on the constituent metals. Because of their intermediate position, the properties of intermetallics can be strongly influenced by small changes in the system (i.e., variations in the microstructure can result in changes in strength and ductility over a considerable range). A great deal of work has been done in the last 10 to 15 years to develop and characterize intermetallics and to develop processing technologies. In response to the need for low density, high performance alloys for use in the components of airframes and turbine engines (NRC, 1993, 1996), for example, concerted efforts have been made in recent years to improve the properties of intermetallic alloys, especially alloys based on aluminides (e.g., TiAl, Ti3Al, NiAl, Ni3Al, FeAl,Fe3Al). Their inherent oxidation resistance and retention of strength at high, homologous temperatures make them prime candidates for use at intermediate temperature ranges, where creep resistant alloys are required. The major problem with many intermetallics is that they can have extremely low ductility at ambient temperatures. Therefor, before they can be used as structural materials, intermetallics must be modified to improve their ductility and strength and to make them more resistant to oxidation and corrosion. In addition, processes must be developed for preparing and processing these materials into usable shapes. [ Last edited by mainpro on 2006-10-17 at 23:10 ] |
回复此楼» 猜你喜欢
0854总分272
已经有4人回复
-
材料工程274求调剂
已经有5人回复
-
272求调剂
已经有8人回复
-
课题组接收材料类调剂研究生
已经有5人回复
-
261求调剂
已经有3人回复
-
化工270求调剂
已经有9人回复
-
考研复试调剂，过国家线的同学都可报名
已经有6人回复
-
0805总分292，求调剂
已经有9人回复
-
0856调剂
已经有8人回复
-
275求调剂
已经有7人回复
ripeach
金虫 (正式写手)
- 应助: 1 (幼儿园)
- 金币: 2119.2
- 散金: 74
- 帖子: 496
- 在线: 32.2小时
- 虫号: 271100
- 注册: 2006-08-12
- 专业: 金属结构材料
2楼2006-10-19 17:23:16
10