High temperature oxidation behavior of Ti3Al–Nb alloys prepared by pulse discharge sintering

Titanium aluminides have received considerable attentions as the basis for new high temperature structural materials. Several compositions based on Ti3Al–Nb have been developed to achieve specific strength and stress rupture properties which exceed those of Ni base alloys such as INCO 718 over temperature range 823–973 K. Recently, pulse discharge sintering (PDS) process technique was successfully developed to manufacture net shape TiAl valves. This research was aimed at investigating the high temperature oxidation of Ti3Al–Nb alloys prepared by PDS. The oxidation rates were measured from 1073–1273 K in air. The kinetics and activation energy for the isothermal oxidation of Ti3Al–Nb alloys revealed that Nb added Ti3Al tended to form finer oxide grain and denser oxide layer and the oxidation rate could be clearly reduced by increasing Nb content (up to 13 at.% in the study). The parabolic rate law was adequate to describe the high temperature oxidation behavior for Ti3Al–Nb alloys in air.