Properties of hot-pressed Al2O3-Fe composites

Alumina-(0 similar to 20 vol. pct) iron composites were fabricated by hot-p ressing of well-mixed-alumina and iron powders at 1400 degreesC and 30 MPa for 30 min. Hot-pressed bodies with nearly theoretical density were obtaine d for addition up to 10 vol. pct Fe, but relative density decreased gradual ly with further increase in Fe addition. The materials exhibit a homogeneou s dispersion of Fe. Fracture strength of the composites exhibits a maximum value of 604 MPa at 15 vol. pct Fe, which is 1.5 times that of alumina alon e. Fracture toughness increases with the increase in Fe content, reaching 7 .5 MPa.m(1/2) at 20 vol. pct Fe. The theoretical values of fracture toughne ss was calculated and compared with the experimental one. Toughening mechan isms of the composites are also discussed.