Cayron, Cyril2020-12-072020-12-072020-12-072020-11-1710.1016/j.scriptamat.2020.11.014https://infoscience.epfl.ch/handle/20.500.14299/173912Recently, a hexagonal phase has been reported in high carbon steels in several studies. Here, we show that the electron microscopy results used in these studies were erroneously interpreted. The extra-spots in the diffraction patterns and the odd contrasts in the high resolution images are not those a superstructure but result from double diffraction and streaking effects due to the presence of twins and stacking faults. We point out a similar unfortunate misunderstanding of these effects in papers reporting the existence of a 9R structure in aluminium or copper, or exotic forms of carbon in diamonds.Electron diffractiontransmission electron microscopymetals and alloyscrystal structureartefacttext::journal::journal article::research article