Influence of in-situ Al ₂O ₃ content on mechanical properties of Al ₂O ₃ reinforced Fe–Cr–Ni alloys

Abstract

In-situ Al ₂O ₃ (14.8–31.3 wt.%) reinforced Fe–Cr–Ni alloys were prepared using reactive hot pressing at a temperature of 700°C and pressure of 30 MPa for 2 h. X-ray diffraction showed that the obtained metal matrix composites (MMCs) mainly comprised Al ₂O ₃, Fe–Cr and Cr _0.7Fe _0.36Ni _2.9 phases. Vickers hardness values of the composites with varying Al ₂O ₃ contents were all around 4.28 GPa. Scanning electron microscopy images showed that the Al ₂O ₃ particles in the MMCs (with Al ₂O ₃ content of 14.8 wt.%) were ultrafine and uniformly distributed. Moreover, the metal matrix composite with 14.8 wt.% Al ₂O ₃ exhibited the highest values of fracture toughness and bending strength, which were 15.2 MPa · m ^1/2 and 529 MPa, respectively.