High-precision face-centered cubic–hexagonal close-packed volume-change determination in high-Mn steels by X-ray diffraction data refinements

Autor: Alberto Baruj, Paulo La Roca, Florencia Malamud, Marcos Sade, Lina Maria Guerrero, Facundo J. Castro
Rok vydání: 2020
Předmět:
Zdroj: Journal of Applied Crystallography. 53:34-44
ISSN: 1600-5767
DOI: 10.1107/s1600576719015024
Popis: High-Mn steels attract attention because of their various technological properties. These are mainly mechanical and functional, such as the shape-memory effect, high damping capacity, high strength with simultaneous large ductility, the TRIP/TWIP (transformation- and twinning-induced plasticity) effect, low cycle fatigue and high work hardening capacity. All these phenomena are associated with the face-centered cubic (f.c.c.)–hexagonal close-packed (h.c.p.) martensitic transformation which takes place in these alloys. During this phase transition defects are introduced, mainly due to the large volume change between austenite and martensite. Knowing this volume change is key to understanding the mechanical behavior of these metallic systems. In the present article, a full-pattern refinement method is presented. The proposed method uses data obtained by means of conventional X-ray diffraction from regular bulk samples and allows a high-precision calculation of the lattice parameters of both phases, f.c.c. and h.c.p., under conditions very different from randomly oriented (powder) materials. In this work, the method is used to study the effect of chemical composition on the volume change between the two structures. By applying empirical models, the results enabled the design and fabrication of Fe–Mn-based alloys with a small volume change, showing the potential of this new tool in the search for improved materials.
Databáze: OpenAIRE
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