Representation of misorientations in Rodrigues–Frank space: application to the Bain, Kurdjumov–Sachs, Nishiyama–Wassermann and Pitsch orientation relationships in the Gibeon meteorite Original Research Article

The three classical orientation relationships describing the γ-to-α transformation, namely the Bain, Kurdjumov–Sachs (K–S) and Nishiyama–Wassermann (N–W), are represented in Rodrigues–Frank (R–F) space. Two alternative reference systems are used to highlight the differences between the three types of misorientation. Some observations obtained on the Gibeon meteorite are analyzed using the two classes of reference system to reveal features of the transformation under conditions of very slow cooling. It is shown that the Bain correspondence relations are never satisfied, while the measurements fall in the full range of direction parallel conditions extending from the K–S to the N–W. The crystallographic features of the Pitsch orientation relation are presented in R–F space in Appendix A. The experimental observations conform to this type of transformation to a considerably lesser extent than to the classical K–S and N–W relations.