The formation of Ni-poor kamacite proceeds by diffusion of Ni in the solid alloy at temperatures between 450 and 700 °C, and can only take place during very slo

The formation of Ni-poor kamacite proceeds by diffusion of Ni in the solid alloy at temperatures between 450 and 700 °C, and can only take place during very slow cooling, about 100 to 10,000 °C/Myr, with total cooling times of 10 Myr or less.[13] This explains why this structure cannot be reproduced in the laboratory. Hmm, [13] https://www.sciencedirect.com/science/article/abs/pii/S0009281909000038?via%3Dihub https://www.sciencedirect.com/science/article/abs/pii/S00092... The wide range of cooling rates for IVA irons and their inverse correlation with bulk Ni concentration show that they crystallized and cooled not in a mantled core but in a large metallic body of radius 150±50 km with scarcely any silicate insulation. This body may have formed in a grazing protoplanetary impact. Uhm, There is a growing consensus that most iron meteorites come from bodies that accreted early – even before the parent bodies of the chondrites – and that 26Al, which has a half-life of 0.7 Myr, is the major heat source that melted them. What? If I understand correctly, it was a large 150km metal blob full of radioactive alumin(iu)m that controlled the crystallization process over millions of years. Now that’s hardcore metal.