| Abstract: | The iron-nickel alloy of the Gibeon octahedrite exhibited a transition from the normal ductile behavior to brittle behavior in tensile tests conducted below 103 °K. This result contradicts data published previously and implies that a temperature-induced transition could explain the fragmentation of a large parent metallic mass into meteorite-sized objects, since the micro-structures of existing octahedrites are consistent with brittle rather than ductile fracture events. Examination of the fractures and microstructures of the tensile specimens affirmed that the observed transition is consistent with meteoritic structures. It is concluded that the mechanical properties of Gibeon meteoritic iron are compatible with both the solid iron core and the metallic “raisin” models for the structure of the parent planet with respect to fragmentation mechanisms. |
