A new method for the investigation of orientation relationships in meteoritic plessite

Abstract

The orientation relationship (OR) between the bcc and fcc phase in the plessite microstructure of the iron meteorites Watson, Agpalilik and Gibeon has been analysed in a scanning electron microscope using electron back-scattered diffraction (EBSD). A very strong OR exists, independently on the analysed plessite type and the observed spreading of single orientation data. The agreement between the experimental orientation distribution and existing models varies for each meteorite. The black plessite in the Agpalilik corresponds to the Nishiyama-Wassermann model whereas the duplex plessite of the Gibeon meteorite shows an OR close to the Kurdjumov-Sachs model. The Watson meteorite is strongly deformed so that a general OR is difficult to determine due to the blurred experimental orientation distribution.

Investigation of orientation relationships by EBSD and EDS on the example of the Watson iron meteorite

“…Please note, that the left cluster shows the same orientation as the surrounding large kamacite crystal. This behaviour of plessite has been already reported in [26] on the Gibeon meteorite.…”

“…In [26] it was shown that plessite similarly presents the same OR as detected for the Widmanstätten macrostructure.…”

“…Recently, the EBSD technique has been applied for the study of OR's in iron meteorites in all [20,22,[24][25][26]. In [26] it was shown that plessite similarly presents the same OR as detected for the Widmanstätten macrostructure.…”

The mechanisms of the fcc–bcc martensitic transformation revealed by pole figures

“…1 obtained on a 9% Cr steel. Similar features appear in many fcc-bcc martensitic materials such as CuZn brasses [3], bainitic steels [4] and FeNi meteorites [5][6][7]. They are not artefacts that could be attributed to the EBSD method, as Bunge et al also observed them by synchrotron X-ray diffraction [8].…”

“…Kurdjumow-Sachs [9] The determination of the OR can be realized either by filtering the PFs [5,6] or by more complex calculations [4]. Most of the time, the singular features around the averaged OR are simulated by a superposition of NW and KS ORs [13,14] or by a higher number of discrete ORs including NW, KS, GT and other intermediate ORs [7].…”