Deformation of iron oxides upon tensile tests at 600-1250°C

Tensile tests of virtually "pure" FeO, gamma-Fe3O4, and alpha-Fe2O3 were performed at 600-1250degreesC at strain rates of 2.0x10(-3) -6.7x10(-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 2.0x10(-4) s(-1). Oxide of gamma-Fe3O4 deformed plastically above 800degreesC Steady-state deformation was indicated at 1200degreesC; elongation of 110% was obtained. Plastic deformation observed at 800-1100degreesC was considered to result from dislocation glide. Using TEM, burgers vector of dislocation observed in deformed gamma-Fe3O4 was determined to be <110>, and its slip system was estimated to be {111}<1 (1) over bar0>. Oxide of FeO deformed plastically above 700degreesC Steady-state deformation became predominant above 1000degreesC Elongation of 160% was obtained at 1200degreesC Strain rates of FeO at 1000 and 1200degreesC were proportional to the fourth power of the saturated stress, indicating that the plastic deformation was affected by dislocation climb.