Ti-Al合金环境脆性机制的电子理论

ENVIRONMENTAL EMBRITTLEMENT OF Ti-ALUMINDES

根据固体与分子经验电子理论（ＥＥＴ）分析计算Ｔｉ－Ａｌ系金属间化合物及氢和氧影响下各相的价电子结构与解理能Ｇｃ，据此分析Ｔｉ－Ａｌ系金属间化合物的环境脆性（ＥＥ）．结果表明，Ｔｉ_３Ａｌ的氢脆是由于高氢含量下易生成性相引起的；ＴｉＡｌ的氢脆是由于固溶氢减弱含氢ＴｉＡｌ晶胞主干键并降低解理能引起的．而Ｔｉ_３Ａｌ固溶氧使其键结构呈更严重的各向异性，导致Ｔｉ_３Ａｌ脆性加剧；在氧含量较高时，氧化物ＴｉＯ_２形成将导致更加恶劣的脆性，而形成最强键ｎＡ和热稳定性较高的Ａｌ_２Ｏ_３将会有好的抗氧化性．同时也解释一些尚有争议的实验结果，并提出一些解决环境脆性的韧化途径．

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.