Effect of raw materials on microstructure and bending strength of porous in situ MgO/Fe–Cr–Ni composites

Porous in situ MgO (17.0–34.9 wt.%)/Fe–Cr–Ni composites were prepared from the mixtures of Mg and the powder compositions, such as nano-Fe2O3 + Cr + Ni, micro-Fe2O3 + Cr + Ni, micro-Cr2O3 + Fe + Ni or micro-Ni2O3 + Fe + Cr, via pressureless reactive sintering at 600–800 °C for 2 h. The influence of raw materials on microstructure and bending strength of the resultant porous composites were studied. The results showed that the porous composites, fabricated at 700 °C for 2 h, consisted of MgO, Cr0.7Fe0.36Ni2.9 and CrFe phases generally. The porous composite fabricated from the mixture of nano-Fe2O3, Mg, Cr and Ni, whose fracture mode was a mainly ductile manner, had uniform pore size and possessed higher bending strength than other resultant porous composites.

► Porous Fe–Cr–Ni/MgO composites were fabricated via pressureless reactive sintering.
► The fracture surface of Fe–Cr–Ni/nano-MgO (34.9 wt.%) showed a mainly ductile manner.
► Fe–Cr–Ni/nano-MgO (34.9 wt.%) had the highest values of bending strength.