Tensile Properties and Microstructure of Squeeze Cast Magnesium Matrix Composite Reinforced with 35 Vol. % of AL₂O₃ Fibers

Magnesium alloy AM60 matrix-based composite reinforced with 35 vol. % of Al₂O₃ fibers were fabricated by preform infiltration and squeeze casting technique under an applied pressure of 90 MPa. For the purpose of comparison, the matrix alloy without reinforcement was also squeeze cast under the same process conditions. Examination of microstructures by both optical microscopy (OM) and scanning electron microscopy (SEM) revealed that alumina fibers were distributed uniformly in the preform. The mechanical properties of the composite were evaluated in comparison with those of the matrix alloy AM60. The Rockwell hardness (HRB) hardness increased from 5.12 to 84.94 as the fiber volume fraction rose from 0 to 35%. The results of tensile testing indicated that the addition of Al₂O₃ fibres to magnesium alloy AM60 led to a significant improvement in mechanical properties. In particular, the modulus of the composite increased to116 GPA by almost three times over that (40 GPa) of the alloy, while the ultimate tensile strength (UTS) rose from 171.36 to 202.56 MPa by 18%. However, the notable increase in both the modulus and strength was at sacrifice in elongation.