ENVIRONMENTAL EMBRITTLEMENT OF Ti-ALUMINDES

The valence electron structures and cleavage energy of Ti-aluminides affected by hydrogen and oxygen arecalculated according to the Empirical electron Theory of Solids and molecules. Environmental embrittlement isdiscussed from the calculable adults. It is expounded that hydrogen embrittlement of Ti3Al alloys is resulted from brittle ( phase forming in high hydrogen content, and that of TiAl resulted from main bond of Crystallattice with hydrogen being wenken and cleavage energy being lowered. Oxygen dissovled in Ti3AI alloysmakes bond structure of Ti3Al very seriously anisotropic, which results in more serious embrittlement.Forma- tion of TiO2 is mere harmful than that of Al2O3, stronger bond and higher heat stability of the latter resultin higher antionxidization.At the same time, some doubtful experimental results are explained, and ways toimprove environmental embrittlement are proposed.