Etch Spirals on Single Crystals of Steel

Two Kinds of Martensitic Transformations in thin Foils of an Fe–32.8 mass%Ni Alloy

“…The Nishiyama relationship has been known to hold for martensites in some ferrous alloys and steels. However, if internal twins of the martensites are those on an exact {112}M twinning plane, the twins must exhibit another orientation relationship different from the Nishiyama's for the austenite matrix, although the Kurdjumov-Sacks relationship holds for both the martensite matrix and its twin (12). Such a different orientation relationship has not been observed experimentally, except for a work by Sato et al (11) on stress-induced bulk martensite, presumably because of a localized formation of twins and a small amount of twinned crystals.…”

Carbon Distribution in Low-Temperature Isothermal Iron-Based Martensite and Its Tetragonality

“…The attempt of a critical experiment was undertaken using the neutron diffraction [24], of which results supported the interpretation given in [17,23] and rejected the hypothesis in [16]. However, the both hypotheses were at variance with results of studies carried out using Mössbauer spectroscopy (see, e.g., [25][26][27]).…”

“…Therefore, the hypotheses attributing the abnormally low tetragonality of virgin martensite to the localization of carbon atoms in the tetrahedral sites [16] or their distribution on the a-, b-, or c-sublattices of octahedral sites [17] (see configurations e and b in Fig. 1) are not consistent with the hyperfine structure of Mössbauer spectra of virgin martensite and their evolution during the heating.…”

“…The abnormally low tetragonality was found after low-temperature martensitic transformation in Fe-Mn-C [12], Fe-Ni-C at a moderate Ni content of 8% [13], Fe-Re-C [14] and plain high carbon [15] martensites. Two main hypotheses have been proposed to interpret the abnormally low tetragonality of the virgin iron-carbon martensite: (i) a partial location of carbon atoms in the tetrahedral interstitial sites resulted from the    martensitic transformation through the intermediate -phase [16]; (ii) a redistribution of carbon atoms among three sublattices of octahedral sites in the bcc crystal lattice due to a twinning on the (011) planes in the course of the low-temperature martensitic transformation [17]. According to the calculations [18], the occurrence of thin twin layers in the -iron lattice on the ] 1 1 0 )[ 011 ( system can shift the maximum of intensity in the X-ray reflections, which seems to be consistent with the second hypothesis.…”

Structure and phase composition of manganese steels modified by alloying elements

“…On the other hand, a great number of stacking faults and dislocation clusters is observed in this steel. Stacking faults were previously considered as a nucleating seed of -phase with HCP crystal system [4][5][6]. Later on, Volosevich [7] proved that the regions with flat dislocation clusters are most favorable for the -phase formation.…”