材料期刊网

在1300℃空气中氧化时,不含稀土的Fe-23Cr-6Al合金的氧化皮迅速起皱,氧化皮/基体界面形成大量空洞.对于预先抛光的试样,空洞在基体表面的晶界上连成网格或分布在与夹杂和碳化物相应的位置.加0.15％La,0.15％Ce或0.60％Y的合金,氧化皮平直,与基体表面密合,其氧化皮内层的晶粒为柱状,晶粒间结合紧密.认为稀土抑制氧化初期热蚀坑的发展及减轻氧化皮在其生长应力作用下产生的蠕变变形,是稀土阻止氧化皮/基体界面形成空洞、改善氧化皮粘附性的原因.

Scales on Fe-23Cr-6Al alloy wrinkle rapidly in air at 1300℃. Cavities andvoids are formed at the scale/substrate interface. For pre-polished specimens, cav-ities are found at the grain boundaries on the metal surface in the form of net-work, and voids occur at places originally occupied by inclusions and carbides.For alloys containing 0.15% La, 0.15% Ce or 0.60% Y, the scales are flat andfree from cavities and voids at the scale/substrate interface. The grains in theinner layer of the scale are columnar in form and adhere tightly to each other.It is considered that the capability of the RE in suppressing the formation of hotcorrosion pits on the alloy surface during the early stage of oxidation and inreducing the creep deformation due to the growth stress in the scale may accountfor the fact that RE addition inhibits the formation of cavities and voids at thescale/substrate interface and improves the adhesion between the scale and the sub-strate.