[meteorite-list] Very strange Nickel Iron structure in a NWA chondrite

[abudka at nycap.rr.com]

Hello Listers,

The nickel-iron structures seen in the droplets at

http://s345.photobucket.com/albums/p384/m42protosun/Bubble%20iron/ 
 
m42protosun 

are dendrites.

A “dendrite indicates a linear, branched structure of which the arms are all parallel to specific 
crystallographic directions” (1).  AND, dendritic morphology (of which there are 
various kinds) always indicates non-equilibrium solidification.  These droplets must have solidified under different gravitational conditions than the 1g we know on earth (perhaps 
microgravity?). 
 
While unusual – but not unknown in the meteoritics world, such structures are 
familiar to casting metallurgists.  Iron dendrites found in pockets and veins in 
the Yanzhuang H6 meteorite are characterized in papers by Li Z. et al. (2) and 
Brooks et Al. (3). 
 
A though experiment: Thicken these dendritic branches, give them more melt 
liquid and more time to grow in low gravity – and what do you have?  The 
Widmanstätten structure! 
 
An alternate interpretation of the meteoritic Widmanstätten structure as a 
primary crystallization, 3-dimensional dendritic structure solidified under 
non-equilibrium microgravity conditions is found at my website, 
 
http://meteormetals.com/ 
 
For background on the circular reasoning behind how meteoritic Widmanstätten 
morphology became the Widmanstätten mechanism, click Learn More at my website. 
 
 
Phyllis Budka 
abudka at nycap.rr.com 
 
References: 
1. Chalmers, Bruce, “Principles of Solidification Processing,” 1977 edition, p. 
92. 
2. Li Z., Xie X., and Zhang D. Meteoritics 27, 249. 
3. Brooks, C., Biery, N., Li Z., Xie X., and Zhang D., Materials 
Characterization 35:165-174 (1995). 

------------------------------------------
Hello lists, with my new Bresser microscope I have detected a structure in 
metalflakes which I can not explain. Has any one seen such a structure in 
meteorites or documentation where it is explalned? 
Look at 
 
http://s345.photobucket.com/albums/p384/m42protosun/Bubble%20iron/ 
 
m42protosun 


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