2005 Volume 45 Issue 12 Pages 1789-1794
Electrolytic iron powder was heated into γ-iron phase and carburized in austenite and its supersaturation phase under the gas mixture of CO and CO2 with carbon activity of 0.1 to 1.0. The spacing of lattice planes of iron was measured using a high temperature X-ray diffractometry (XRD), which gradually increased with time and arrived at a constant value. The carbon concentration in samples after experiment was measured by a combustion-infrared absorptiometry. The lattice constants, a0 (nm), of α-iron, γ-iron and austenite including its supersaturation phase of carbon have been determined as follows;
α-iron: a0=1.602×10-9T2+2.059×10-6T+0.2860 (295 to 1183 K)
γ-iron: a0=8.1593×10-6T+0.35519 (1183 to 1550 K)
Austenite: a0=0.35519+8.1593×10-6T+1.7341×10-3C (0 to 3.35 masss% and 1452 to 1550 K)
where T and C are temperature (K) and carbon concentration (mass%), respectively.
