Microstructure evolution and mechanical properties of nano-SiCp/AZ91 composite processed by extrusion and equal channel angular pressing (ECAP)

Journal Article · Tue Nov 15 04:00:00 EST 2016 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2016.10.003· OSTI ID:22689658

Qiao, X. G.; Ying, T. ^[1]; Wei, E. D.; Wu, K.; Hu, X. S. ^[1]; Gan, W. M.; Brokmeier, H. G. ^[2]; Golovin, I. S. ^[3]

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1. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)
2. Institute of Materials Research, Helmholtz-Centre Geesthacht, D-21502 Geesthacht (Germany)
3. Department of Physical Metallurgy of Non-Ferrous Metals, National University of Science and Technology “MISiS”, Leninsky ave. 4, 119049 Moscow (Russian Federation)

Nano-SiCp/AZ91 magnesium matrix composite was fabricated by stir casting. The as-cast ingots were extruded at 350 °C, then processed by equal channel angular pressing (ECAP) at various temperatures (250 °C, 300 °C and 350 °C). Grains are significantly refined after the extrusion and the ECAP. A basal fibre texture was detected by neutron diffraction after the extrusion, which inclines about 45° to the extrusion direction (ED) after the ECAP. Nano-scaled SiC particles agglomerate in the as-cast composite. After the extrusion, the agglomeration tends to form continuous or discontinuous strips along the extrusion direction. By application of the ECAP, the agglomerated SiC particles are partly dispersed and the strips formed during the extrusion tend to be thinner and broken with the increasing pass number. The yield tensile strength (YTS) and the ultimate tensile strength (UTS) of the composite are dramatically increased after the extrusion. ECAP for one pass at various temperatures further increases the strength, however, the YTS decreases with the increasing ECAP temperature and the pass number. The Orowan equations predict the maximum YTS of the composite may be up to 400 MPa providing SiC particles are homogenously distributed in the matrix. - Highlights: •Nano-scaled SiC particles were successfully added into AZ91 by stirring casting. •Agglomeration of nano-particles were improved by extrusion and ECAP. •Yield strength of the composite is 328 MPa after one pass of ECAP. •Further ECAP process with optimized parameters may fully disperse nano-particles. •Yield strength is predicted to up to 400 MPa when particles are fully dispersed.

• OSTI ID: 22689658
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 121; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGGLOMERATION
CASTING
EXTRUSION
FIBERS
MAGNESIUM
MATRICES
MICROSTRUCTURE
NANOCOMPOSITES
NEUTRON DIFFRACTION
PRESSING
SILICON CARBIDES
STIRRING
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
YIELD STRENGTH
YIELDS