Nanoscale twinning in Fe–Mn–Al–Ni martensite: a backscatter Kikuchi diffraction study. Issue 1 (5th December 2020)

• Record Type: Journal Article
• Authors: Fischer, Peter D. B.; Martin, Stefan; Walnsch, Alexander; Thümmler, Martin; Kriegel, Mario J.; Leineweber, Andreas
• Is Part Of: Journal of applied crystallography. Volume 54:Issue 1(2021)
• Page Start: 54
• Page End: 61
• Publication Date: 2020-12-05
• Subjects: electron backscatter diffraction -- martensite -- shape‐memory alloys -- twinning -- backscatter Kikuchi diffraction; Crystallography -- Periodicals; 548.05
• DOI: 10.1107/S1600576720013631
• Languages: English
• ISSNs: 0021-8898

Abstract

Abstract : Fe–Mn–Al–Ni martensite distortion gives rise to complex backscattered Kikuchi diffraction patterns which cannot be interpreted by standard procedures. Analysis of these patterns reveals that they arise from nanoscale internal twinning and tetragonal distortion of the basically cubic close‐packed martensite. Abstract : Iron‐based Fe–Mn–Al–Ni shape‐memory alloys are of rather low materials cost and show remarkable pseudoelastic properties. To further understand the martensitic transformation giving rise to the pseudoelastic properties, different Fe–Mn–Al–Ni alloys have been heat treated at 1473 K and quenched in ice water. The martensite, which is formed from a body‐centred cubic austenite, is commonly described as face‐centered cubic (f.c.c.), even though there are also more complex, polytypical descriptions of martensite. The presently studied backscatter Kikuchi diffraction (BKD) patterns have been evaluated, showing a structure more complex than simple f.c.c. This structure can be described by nanoscale twins, diffracting simultaneously in the exciting volume. The twinned structure shows a tetragonal distortion, not uncommon for martensite in spite of the lack of interstitial elements. These features are evaluated by comparing the measured BKD patterns with dynamically simulated ones.