The oxidation behavior of LaB6-ZrB2 eutectic in situ composites prepared by electric arc melting was studied at 916 to 1223C and 1.5 x 104 to 7.2 x 104Pa. The specific weight change of the eutectic obeyed the Arrhenius equation below the oxidation temperature of 1094C, and appeared to obey a paralinear equation above this temperature. The rate of weight change was described by kp(mg2/cm4min) = 9.71 x 10-3exp[-31000/RT] at 916 to 1094C. Above 1094C, rapid oxidation kinetics were observed: La2O3·B2O3 and La2O3·3B2O3 being the primary scale constituent, with a ZrO2 deficiency in the outer scale. The oxidation increased with PO2 up to 3.9 x 104Pa; above which the trend was reversed due to the active oxidation of ZrB2. The oxidation appeared to be controlled by oxygen diffusion through the scale and the oxidized layers consisted mainly of La2O3·B2O3, La2O3·3B2O3 and a trace of ZrO2.

High Temperature Oxidation of LaB6-ZrB2 Eutectic in situ Composite. Chen, C.M., Zhang, L.T., Zhou, W.C., Li, M.Q.: Acta Materialia, 1999, 47[6], 1945-52