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Title: Metal/ceramic interface structures and segregation behavior in aluminum-based composites

Trimodal Al alloy (AA) matrix composites consisting of ultrafine-­grained (UFG) and coarse-­ grained (CG) Al phases and micron-­sized B 4C ceramic reinforcement particles exhibit combinations of strength and ductility that render them useful for potential applications in the aerospace, defense and automotive industries. Tailoring of microstructures with specific mechanical properties requires a detailed understanding of interfacial structures to enable strong interface bonding between ceramic reinforcement and metal matrix, and thereby allow for effective load transfer. Trimodal AA metal matrix composites typically show three characteristics that are noteworthy: nanocrystalline grains in the vicinity of the B4C reinforcement particles; Mg segregation at AA/B 4C interfaces; and the presence of amorphous interfacial layers separating nanocrystalline grains from B 4C particles. Interestingly, however, fundamental information related to the mechanisms responsible for these characteristics as well as information on local compositions and phases are absent in the current literature. Here in this study, we use high-­resolution transmission electron microscopy, energy-­dispersive X-­ray spectroscopy, electron energy-­loss spectroscopy, and precession assisted electron diffraction to gain fundamental insight into the mechanisms that affect the characteristics of AA/B 4C interfaces. Specifically, we determined interfacial structures, local composition and spatial distribution of the interfacial constituents. Near atomic resolution characterization revealed amorphousmore » multilayers and a nanocrystalline region between Al phase and B 4C reinforcement particles. The amorphous multilayers consist of nonstoichiometric Al xO y, while the nanocrystalline region is comprised of MgO nanograins. The experimental results are discussed in terms of the possible underlying mechanisms at AA/B 4C interfaces.« less
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  1. Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences Directory
Publication Date:
Report Number(s):
Journal ID: ISSN 1359-6454
Grant/Contract Number:
AC52-07NA27344; AC02-05CH11231; N00014-13-1-0668; N00014-12-1-0237; 12-LR-238313
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 95; Journal Issue: C; Journal ID: ISSN 1359-6454
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; Aluminum alloy; Transmission electron microscopy; Segregation; Interface
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1251514