TEM investigation of non-crystallographic displacements near antiphase domain boundaries in D0{sub 3} ordered Fe{sub 3}Al

Journal Article · Mon Nov 02 04:00:00 EST 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00264-X· OSTI ID:302354

Liu, W; Nembach, E ^[1]; Gemperle, A; Gemperlova, J; Paidar, V ^[2]

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1. Westfaelische Wilhelms-Universitaet Muenster (Germany). Institut fuer Metallforschung
2. Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Physics

Antiphase domain boundaries (APBs) have been studied by means of transmission electron microscopy in a D0{sub 3} long-range ordered Fe{sub 3}Al single crystal. Two types of APB contrasts have been observed. The normal {pi}-type APB contrast was imaged with superlattice reflections. This type of contrast is caused by the basic displacement R{sub 0} = 1/4{l_angle}111{r_angle} or 1/2{l_angle}111{r_angle} across the APB. On the other hand, the anomalous {alpha}-type APB contrast was imaged with fundamental reflections. The latter contrast was weak, asymmetric in dark field and discontinuous along a close APB loop. It has been demonstrated that the anomalous {alpha}-type contrast is caused by a small non-crystallographic displacement r of atoms near the APBs. Detailed examination of the anomalous APB contrast indicated that the fault vector r depends on the basic displacement R{sub 0} as well as on the APB orientation. The main component of r was found to be perpendicular to the APBs with R{sub 0} = 1/4{l_angle}111{r_angle}. The addition displacement is discussed in terms of the mechanical and chemical relaxations of the APBs and with reference to the anomalous plastic behavior of Fe{sub 3}Al.

• OSTI ID: 302354
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 17 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CRYSTAL DEFECTS
DEFORMATION
INTERMETALLIC COMPOUNDS
IRON BASE ALLOYS
PLASTICITY
TRANSMISSION ELECTRON MICROSCOPY