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Mechanical properties of NiAl-Mo composites produced by specially controlled directional solidification

Published online by Cambridge University Press:  29 November 2012

G. Zhang
Affiliation:
Institute for Physical Metallurgy and Metal Physics, RWTH Aachen University, Kopernikusstraße 14, D-52074 Aachen, Germany
L. Hu*
Affiliation:
Institute for Physical Metallurgy and Metal Physics, RWTH Aachen University, Kopernikusstraße 14, D-52074 Aachen, Germany
W. Hu
Affiliation:
Institute for Physical Metallurgy and Metal Physics, RWTH Aachen University, Kopernikusstraße 14, D-52074 Aachen, Germany
G. Gottstein
Affiliation:
Institute for Physical Metallurgy and Metal Physics, RWTH Aachen University, Kopernikusstraße 14, D-52074 Aachen, Germany
S. Bogner
Affiliation:
Foundry Institute, RWTH Aachen University, Intzestraße 5, 52056 Aachen, Germany
A. Bührig-Polaczek
Affiliation:
Foundry Institute, RWTH Aachen University, Intzestraße 5, 52056 Aachen, Germany
*
*Correspondent author. Tel.: +49 (0) 241 80 20 25 7; fax: +49 (0) 241 80 22 30 1. E-mail address: hulei@imm.rwth-aachen.de
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Abstract

Mo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

Type
Articles
Copyright
Copyright © Materials Research Society 2012 

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