Mechanical properties of iron meteorites and the structure of their parent planets

Abstract

The strength and ductility of metal from the meteorite Gibeon have been determined over a range of temperatures and strain rates. The room temperature yield strength is 3.2 kb and the elongation at fracture, 19%; these quantities are much less sensitive to temperature and strain rate in the Gibeon metal than in pure iron. There is no evidence of embrittlement of the metal in Gibeon by nonmetallic inclusions. Fragmentation of a mass of this metal would occur by ductile rather than by brittle fracture. The absence of structural evidence of ductile fracturing strongly suggests that the Gibeon irons are not fragments of some larger metal mass, such as a planetary core, but existed as separate metal pieces surrounded by stony material in the parent planet. The available evidence indicates that a similar conclusion probably can be drawn for most iron meteorites.