Investigating the microstructure-property relationship in Mg matrix composites reinforced by particles of different sizes using experiments combined with finite element simulation

In this study, Ti particles (size of 45, 38, 15, and 5 μm) with a mass fraction of 5% reinforced the Mg-9Al-1Zn (AZ91) magnesium matrix composites are fabricated via spark plasma sintering method. Microstructure observation reveals the interfacial zone is composed of Mg17Al12 and Al-rich phase products. Mechanical testing demonstrates that the elongation of the AZ91-Ti (15 μm) composite reaches the peak value of 21.8%, the ultimate tensile strength can be maintained at 211 MPa, and the optimal elastic modulus is up to 47.85 GPa. The composites maintain high strength mainly through heterogeneous deformation induced (HDI) strengthening and thermal mismatch strengthening. From finite element simulation analysis, the relative small size of Ti particles can restrain strain concentration and facilitate stress conduction, making the strain and stress distributing uniformly. Ti particles with appropriate size can enhance the work hardening capacity, leading the AZ91-Ti composite to possess excellent comprehensive mechanical performance.