High-Temperature Oxidation of Ti₅Si₃ in Air

Abstract

The oxidation behaviour of Ti₅Si₃ was assessed by thermogravimetry in a temperature range 1400 to 1600K in ambient air for 100ks. Detailed metallographic examinations were performed using conventional methods for the specimens oxidised under specified conditions. The kinetics follows nearly cubic laws at 1400 and 1500K, and at 1550K for up to 50ks when a breakaway starts. During the cubic oxidation two-layer scales are formed; the outer layer is rutile while the inner layer is amorphous silica with the activation energy of 262kJ·mol^-1 At 1600K the scale consists of an outer rutile layer and a porous inner layer which is a mixture of rutile and silica grains. Thus, the scale is not protective.