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Indexed by:期刊论文

Date of Publication:2008-02-25

Journal:MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Included Journals:SCIE、EI

Volume:475

Issue:1-2

Page Number:194-201

ISSN No.:0921-5093

Key Words:AZ91 magnesium alloy; semisolid; microstructure; tensile properties

Abstract:AZ91 magnesium alloy was semisolid processed under experimental conditions designed to yield from 3 to 40% of the primary particles, and the semisolid slurry was produced by electromagnetic stirring after feedstock had been isothermally heat treated at near-liquidus temperature. The thixotropic microstructures obtained were characterized in detail and linked to the corresponding tensile proper-ties. A unique microstructure was exhibited that the primary particles conglutinated together to form clusters due to sliding between solid particles and plastic deformation of solid particles during semisolid deformation [C.P. Chen, C.-Y.A. Tsao, Acta Mater. 45 (5) (1997) 1955-1968] which resulted from electromagnetic stirring. An increase of solid fraction exacerbated this agglomerating phenomenon accompanying an increment Of beta-Mg17Al12 content, and those finally resulted in a reduction in elongation. The fractographic analysis revealed that fracture mechanism and corresponding morphology of the rapture surface of tensile bars depend on the solid fraction of the primary particles. (c) 2007 Elsevier B.V. All rights reserved.