Nanocrystalline NiA1 - processing, characterization and mechanical properties.

Journal Article · Sun Nov 15 04:00:00 EST 1998 · Mater. Sci. Eng. A

DOI:https://doi.org/10.1016/S0921-5093(98)00810-7· OSTI ID:938347

Choudry, M S; Dollar, M; Eastman, J A

Nanocrystalline ordered NiAl (n-NiAl) was successfully synthesized by an electron beam gas condensation and compacted in-situ at various temperatures. As-compacted material exhibits grain sizes between 2 and 4 nm and densities between 78 and 94% of the theoretical density, increasing with increasing compaction temperature above all as a result of reduced porosity. The nanocrystalline structure of NiAl is stable up to about 1000 C. Microhardness of as compacted n-NiAl increases with increasing density, above all as a result of reduced porosity. For the reasons not fully understood yet, microhardness of n-NiAl increases also with increasing grain size following annealing, a response different from that in the conventional, coarse-grained NiAl, The present material is significantly stronger than its conventional counterpart but not as strong as predicted by Hall-Petch-type modeling. Also, in the nanocrystalline form, NiAl exhibits room temperature ductility, unlike its coarse-grained counterpart. The present study provides probably the first unequivocal experimental evidence of the room temperature ductility of a nanocrystalline intermetallic material. The mechanical behavior of n-NiAl can be rationalized assuming that diffusional, rather than dislocation, mechanisms control strength and ductility of n-materials.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: ER
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 938347
• Report Number(s): ANL/MSD/JA-29505
• Journal Information: Mater. Sci. Eng. A, Journal Name: Mater. Sci. Eng. A Journal Issue: 1-2 ; Nov. 15, 1998 Vol. 256; ISSN 0921-5093; ISSN MSAPE3
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
DUCTILITY
ELECTRON BEAMS
GRAIN SIZE
MECHANICAL PROPERTIES
MICROHARDNESS
POROSITY
PROCESSING