Formation of structure defects on martensite transformations results in azimuthal tailing of diffraction reflections of single-crystalline samples. From the magnitude of tailing and from the increase of the misorientation angle of crystal lattice regions after multiple martensitic transformations, one can deduce the capability of fragmentation and grain refinement of an austenite phase [4, 6]. In Fe-based alloys, three types of martensitic transformations are realized: γ-α-γ in Fe-Ni-based alloys with face-centered cubic (f.c.c.)-body-centered cubic (b.c.c.)-f.c.c. structure rebuilding, γ-ϵ-γ in Fe-Mn-based alloys with f.c.c.-hexagonal Stattic research buy close-packed (h.c.p.)-f.c.c. transformation [7], and

γ-ϵ′-γ in Fe-Mn-based alloys with f.c.c.-18-layer rhombic (18R)-f.c.c. transformation [8, 9]. It is shown experimentally that the AZD1390 cost restoration of the initial austenite structure after cyclic γ-ϵ-γ and γ-ϵ′-γ transformations turned out to be superior against that of alloys with γ-α-γ transformations. This regularity is based on the fact that the density of buy BLZ945 dislocations increases by more than 103 after cyclic γ-α-γ transformations connected with a high volume change – up to 3% to 4%, while it increases only by 10 after cyclic γ-ϵ-γ transformations (with a smaller volume change – up to approximately 0.75%) and practically does not change after γ-ϵ′-γ transformations (volume change – up

to approximately 0.5%) [4, 7]. In the austenitic phase,

additional subgrain boundaries can form under conditions of dislocation generation by direct and reverse martensite transformations, for example, by means of wall formation by one-sign dislocations. On account of these processes, the fragmented structure of reverted austenite is received. The process of structure fragmentation can be essentially different for alloys with different types of martensitic transformations. In the present article, the effect of multiple martensitic transformations of different types is studied in Fe-Ni- and Fe-Mn-type alloys. The development of austenitic structure fragmentation and the capability of particular alloys to form highly dispersive structures due to the accumulation of structure defects are elucidated. Methods The following RANTES alloys: Fe – 24.8 wt.%, Ni – 0.50 wt.%, C (alloy 1); Fe – 19.5 wt.%, Mn – 2 wt.%, Si (alloy 2); Fe – 16.7 wt.%, Mn – 0.45 wt.%, C (alloy 3), and Fe – 15.2 wt.%, Mn – 0.32 wt.%, C (alloy 4), were chosen for the investigation. All the alloys were melted in a furnace in purified argon. Single-crystalline samples (∅ 0.8 mm, L = 5 to 10 mm in size) for X-ray investigations in an RKV-86 (Moscow, USSR) rotational camera were cut out from large grains of the bar. All the alloys display an austenitic structure at room temperature after quenching from 1,000°C to 1,050°C in cold water.