Aging behavior of AZ91 matrix influenced by 5 μm SiCp: Investigation on the microstructure and mechanical properties

The aging behavior of AZ91 matrix influenced by 5 mm SiCp was studied in present work. The result showed that both discontinuous and continuous precipitation occurred in the monolithic AZ91 alloy during aging treatment. Addition of SiCp led to the decrease of discontinuous precipitate in AZ91 matrix. With the increase of SiCp's content, the amount of discontinuous precipitates decreased which was accompanied by the increased amount of continuous precipitates. Compared with promoting effect of grain refinement on the nucleation and growth of discontinuous precipitate, the SiCp played a more important role on suppressing discontinuous precipitation. Despite the fact that the improved YS of SiCp/AZ91 composite changed a little as the content of SiCp increased from 2vol. % to 15vol. %, the increase of improved UTS was obvious owing to the increased amount of continuous precipitate. Furthermore, aging precipitation, grain refinement, dislocation strengthening and load transfer effect constituted the strengthening mechanism of as-aged SiCp/AZ91 composites, and the aging precipitation strengthening played a leading role among them. (C) 2017 Elsevier B.V. All rights reserved.