TEM studies of the influence of the orientation on the dislocation structures in plastically deformed Ni₃Al single crystals

Autor(en)

H. P. Karnthaler, C. Rentenberger, E. Muhlbacher

Abstrakt

Ni₃Al shows like many other L1₂ alloys an anomalous increase of the yield stress up to a peak temperature of about 800 °C. This increase is generally explained by a thermal activated cross slip process of superlattice screw dislocations from (111) to (010). To study the influence of the external stress on this process two orientations were selected: compression axis [1̄23] and [001]. They show a large difference of the Schmid factors for cube cross slip. Single crystals of Ni₃Al were deformed at RT and 400 °C, and TEM foils cut parallel to (111) and (010) were studied. At RT which is below the anomalous temperature regime the dislocation structures are in both cases similar to those of fcc structures without an order. At 400 °C the TEM results show a distinct difference: dislocations bowing out on (010) are a typical feature for the [1̄23] axis; whereas in the case of the [001] axis dislocation reactions and long straight screws are predominant. They occur in the form of KW locks and contain frequently SISF converted KW locks. Therefore, despite of the different appearance, in both cases strong obstacles are contained in the observed dislocation structures. To overcome these strongly locked segments an Orowan type source model is proposed. When the stress is sufficiently high the dislocation can bow out between obstacles, move on and leave the locked segments behind, which are stored.

Organisation(en)

Physik Nanostrukturierter Materialien

Externe Organisation(en)

Universität Wien

Band

288

Seiten

293-298

Anzahl der Seiten

6

DOI

https://doi.org/10.1557/PROC-288-293

Publikationsdatum

1992

Peer-reviewed

Ja

ÖFOS 2012

103042 Elektronenmikroskopie, 103018 Materialphysik

ASJC Scopus Sachgebiete

Allgemeine Materialwissenschaften, Condensed Matter Physics, Mechanics of Materials, Mechanical Engineering

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/7c46aef3-13e3-4fa2-9835-02997fc22278