An effect of contact melting in the Sikhote-Alin iron meteorite after isentropic spherical shock waves loading
The results of investigation of structural changes in samples of the Sikhote-Alin iron meteorite after spherical explosive loading are presented. Areas of this meteorite connected with contact melting on kamacite (α-Fe(Ni,Co), Ni<7,5 %) and rhabdite ((Fe,Ni)3P) interface are studied in detail using scanning electron microscopy and optical microscopy. It’s supposed that above mentioned areas were formed during local rise of temperature in compression stage. Faceted phosphides can be completely melted or partially melted with edging formation around untransformed phosphide. The aim of this work was to determine phase and chemical composition of this edging. Space distribution of elements and chemical composition of contact melting area were studied using EDS. Low content of phosphorus and nickel in comparison with unaltered part of phosphide has been found. Content of this area complies with content of three-component eutectic and temperature in areas of contact melting exceeded 950 °С. Phase and orientation maps were obtained using EBSD technique. One can supposed after an analysis of this maps that this edging has polycrystalline structure with bcc lattice, i.e. this structure which was formed during contact melting can be considered as supersaturated solid solution of phosphorus in α-Fe (Ni, Co).