Effects of in situ composite ceramics on the mechanical properties and microstructure of Fe–Cr–Ni alloys

Abstract

Fe–Cr–Ni composites reinforced with Al2O3–MgO composite ceramics were prepared via reactive hot pressing at 800 °C for 2 h under 30 MPa. The composites primarily comprised Cr0.19Fe0.7Ni0.11, Fe–Cr, magnesium aluminate spinel, Al2O3, and MgO phases. The mechanical properties and microstructure of the metal matrix composites changed with the changing in situ Al2O3–MgO content. The composite ceramic exhibited excellent mechanical properties (Vickers hardness = 5.59 GPa, bending strength = 244.59 MPa, and fracture toughness = 11.66 MPa·m1/2) when Al2O3/(MgO + Al2O3) (mol/mol) was 0.6371 owing to the difference in the residual stress at the interface between the ceramic particles and metal matrix.