Microstructures and mechanical properties of the in-situ formed nanocomposites of (ZrB2 + Al2O3) and AA7055 alloy

In the present work, direct melt reaction method was employed to fabricate the in-situ nanocomposites of (ZrB2 + Al2O3) and AA7055 alloy. The microstructures, tensile properties, hardness and porosity were further inves-tigated. The grain sizes are greatly refined from 102.4 mu m to 21.7 mu m and particle clusters distributing along grain boundaries are smaller than the situation with monotonous particle reinforcing. The ultimate tensile strength increases from 526.3 MPa to 593.8 MPa without elongation loss and the hardness from 178.0 HV to 216.7 HV as the increasing particles. The effects of (ZrB2 + Al2O3) nanoparticles on microstructures and me-chanical properties were discussed.