Tensile behavior and plastic deformation mechanism of SiC_p/AZ91D magnesium matrix nanocomposites at room temperature

Abstract

To obtain magnesium matrix composites with high strength and high plasticity, SiCp/AZ91D magnesium matrix nanocomposites with uniform dispersion of SiC nanoparticles were prepared by high intensity ultrasonic dispersion method and metal mold gravity casting process, following by T4 solution heat treatment and the tensile test at room temperature. The microstructure and plastic deformation mechanism of the specimen after tensile test were investigated by scanning electron microscope and transmission electron microscope. The results show that the tensile strength and elongation of nanocomposites reach up to 296 MPa and 17.3% at room temperature, respectively. A large number of twins and slip are observed in SiCp/AZ91D magnesium matrix nanocomposites with T4 state after tensile deformation at room temperature. It is obvious that twinning and slip are the main mechanisms of plastic deformation in the nanocomposites.High strain zones are formed around SiC nanoparticles in the α-Mg matrix during the tensile process at room temperature, and a lot of dislocations and stacking faults are formed in the high strain zones. These dislocations and stacking faults are evolved into a large number of slip bands and twins under the action of tensile strain, which is the plastic deformation mechanism of SiCp/AZ91D magnesium matrix nanocomposites with high plasticity at room temperature.

Keywords

• magnesium matrix nanocomposites
• tensile
• twinning
• slip
• plastic deformation mechanism