Microstructure Evolution and Improved Creep Behavior of Mg-Al-Si Alloy Matrix Composite Reinforced with SiC Nanoparticles
The Mg-9Al-1Si matrix composite reinforced with SiC nanoparticles is fabricated by semisolid stirring-assisted ultrasonic vibration, which contains finer grains and a more uniform microstructure compared to that of the Mg-9Al-1Si alloys. The sizes of the Mg17Al12 and Mg2Si phases decreased continuously as the volume fraction of n-SiCp increased from 0 to 1% and then increased apparently when the volume fraction of n-SiCp increased to 1.5%. The steady-creep rates of the 1 vol.% n-SiCp/Mg-9Al-1Si are approximately two times lower than those of the Mg-9Al-1Si matrix alloy at 200 °C under applied stress of 70 MPa due to the strengthening effect of the nanosized SiCp. The reason for the improved creep properties is mainly attributed to the obvious grain boundary strengthening, the Orowan strengthening mechanism, the load transfer effect, and the pinning effect of the n-SiCp and the refined Mg17Al12 and Mg2Si phases.
Keywordscreep resistance magnesium matrix composite microstructure SiC nanoparticles strengthening mechanism
This work was supported by the National Natural Science Foundation of China (Nos. 51301118, 51375464 and 51404166), the National Natural Science Foundation of Shanxi Province (No. 201701D121045), Shanxi Province Scientific Facilities and Instruments Shared Service Platform (No. 201805D141005) and the Shanxi Key Laboratory of Advanced Magnesium-Based Material, Taiyuan University of Technology (AMM-2017-12).
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