Tensile deformation of iron oxides at 600-1250°C

Tensile tests of virtually "pure'' FeO, gamma-Fe3O4, and alpha-Fe2O3 were performed at 600-1250degreesC at strain rates of 2.0 x 10(-3)-6.7 x 10(-5) s(-1) under controlled gas atmospheres. Mechanical properties and deformation/fracture behavior were investigated. For alpha-Fe2O3, brittle fracture resulted at 1150-1250degreesC and the fracture strain was below 4.0% at a strain rate of 2.0 x 10(-4) s(-1). gamma-Fe2O4 deformed plastically above 800degreesC. Steady-state deformation was indicated at 1200degreesC; elongation of 110% was obtained. Plastic deformation observed at 800 to 1100degreesC was considered to result from dislocation glide. Using TEM, the Burgers vector of dislocations observed in deformed gamma-Fe2O4 was determined to be [110], its slip system was estimated to be {111}[1 (1) over bar0]. FeO deformed plastically above 700degreesC. Steady-state deformation became predominant above 1000degreesC. Elongation of 160% was obtained at 1200degreesC. Strain rates of FeO at 1000degreesC and 1200degreesC were proportional to the fourth power of the saturated stress, indicating that plastic deformation was affected by dislocation climb.