合金元素Y对高铌TiAl高温合金长期抗氧化性的影响

Influence of Y-Addition on the Long-Term Oxidation Behavior of High Nb Containing TiAl Alloys

研究不同含Y量对高铌TiA l合金在900℃恒温条件下,1000h的抗氧化性的影响。结果发现,从长期看,氧化速率、氧化膜结构以及氧化膜抗剥落能力均与Y含量有关。在900℃等温氧化条件下,0.4 at%Y含量能有效提高高铌TiA l合金的抗氧化性,而高Y含量对与抗氧化性的负面影响在氧化初始阶段已经十分明显。通过对氧化后样品SEM和EDS分析发现,适量Y元素的加入可以细化氧化物颗粒,促使合金表面形成连续A l2O3保护膜,提高氧化膜与合金基体的粘附性,从而提高高铌TiA l合金的高温长期抗氧化性。

Influence of Y-addition on the long-term oxidation behavior of high Nb containing TiAl alloys was studied. The results showed that the oxidation rates, structures of scale as well as the scale spallation resistance were closely related to the concentrations of Y. Under isothermal oxidation at 900℃, a small amount of Y-addition （0.4at%） was effective in improving the oxidation resistance. However, the alloys with higher Y contents （0.6 and 0.8 at% ） had a detrimental effect on the oxidation resistance after initial isothermal exposure. Oxidized samples were examined by scanning electron microscopy （SEM） ,energy dispersive x-ray analysis （EDX） and x-ray diffraction analysis（ XRD）, it was found that a small amount of Y-addition （0.4at%） was effective in improving the oxidation resistance by refineing the oxide particles, promoting formation of a protective continuous Al2O3 scale and improving the adherence of the oxide scale.