Ishi Miura

Oxidation of titanium-iron alloys at high temperatures in air

Oxidation of Ti-Fe alloys at high temperature was investigated mainly by measuring the weight change due to the formation of oxidation layers. Measurements were made on a specimen cross section and the authors have considered on the hardness penetration in the time of oxidation.The specimens were Kroll titanium, 1%Fe, 2%Fe. 4%Fe and 8%Fe alloys and heated in the air at 600, 700, 800 and 900°C.Generally speaking, parabolic rate law, (Δm)=Kp·t+C, was applicable to the oxidation of Kroll titanium and Ti-Fe alloys in the range 600-900°C.Authors have gained the value of the parabolic oxidation rate constant for all the specimens at each oxidation temperature. The relations between the logarithms of experimentally determined Kp and 1/T were straight lines except the oxidation of 4%Fe and 8%Fe alloys.Activation energies were calculated from the diagram, they were 58700, 66000 and 57000cal/mol respectivery for Kroll titanium, 1%Fe and 2%Fe alloys.Hardness penetration was deeper as the alloying element increases for the same oxidation temperature and time.X-ray analysis of the oxidation layers showed only strong reflections of rutile even for 8%Fe alloy which was oxidized at 900°C for 25 hours.