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Orientation Relationships in the System Nb-NbCr2

Published online by Cambridge University Press:  02 July 2020

P. G. Kotula
Affiliation:
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545
K. C. Chen
Affiliation:
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545
D. J. Thoma
Affiliation:
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545
F. Chu
Affiliation:
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545
T. E. Mitchell
Affiliation:
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545
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Extract

Laves-phase intermetallics are of potential use as high-temperature structural materials. NbCr2-based C15-structured alloys are of particular interest for such applications. by themselves, Laves phases generally have poor ductility and fracture toughness at low temperatures. Two phase alloys (i.e., Laves phase and the ductile bcc phase) are considered more promising for structural applications. The orientation relationships between the two phases can contribute to the mechanical behavior of the material. In this study, observations of two different orientation relationships in a Nb-NbCr2 eutectic are discussed and compared with previous studies of the NbCr2 system, as well as the TiCr2 system.

A Nb-NbCr2 eutectic alloy was prepared by arc-melting high-purity alloys followed by annealing at 1400°C for 100 h and then cooling at l°C/min. The complete details of the materials preparation have been given elsewhere. Specimens were prepared for observation in the transmission electron microscope (TEM) by cutting 3 mm discs with a coring saw, followed by dimpling and ion milling. Microstructural characterization was performed with a Philips CM30 TEM operating at 300 kV.

Type
Phase Transformations in Metals and Alloys
Copyright
Copyright © Microscopy Society of America 1997

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