Neumann lines
Neumann lines are parallel sets of very fine, sometimes crossing lines in iron meteorites. They become visible when a certain type of iron meteorite , namely hexaedrites , which only consist of kamacite , is ground, polished and etched with methanol- containing nitric acid. These lines should not be confused with the Widmanstätten structure , which is coarser and does not appear in hexahedrites.
It is assumed that the cause of this structure is a shock process, for example when meteorites hit asteroids .
Neumann lines also occur z. B. in the lattice structure of deformed metals by detonation. Here they are used, among other things, to prove the effects of explosives on components. They are created by compressing the microstructural metal mesh.
If one imagines a row of marbles or spheres of the same size instead of the metal atoms, the neighboring "marbles" lie next to each other so that each marble only touches one marble in the neighboring row. Due to the action of great forces, the row of marbles is now shifted so that each marble touches two marbles in the neighboring row. She was pushed into the gaps.
Neumann lines are named after Johann G. Neumann , who discovered them in 1848 in the hexaedrite Braunau , who fell in 1847 near Broumov (Braunau), now the Czech Republic .
See also
Individual evidence
- ^ Johann G. Neumann: About the crystalline structure of the meteor iron from Braunau. In: Naturwissenschaftliche Abhandlungen Wien. 3, 1849, pp. 45-56.
- ^ John G. Burke: Cosmic Debris. Meteorites in History. University of California Press, 1986, ISBN 0-520-05651-5 .