Abstract: In Fe-20Cr-4Al-0.5Si-(0.13-0.73)Y alloys,a new phase consisting of 15.8 wt-% Y,65.4 wt-% Fe,12.6 wt-% Cr,4.4 wt-% Al and 1.4 wt-% Si was observed with its Y-content and crys- tal structure being identical with those of YFe_9 phase basically and the microhardness being 4-5 times higher than that of α-phase matrix.It is a kind of stable particles (2-10 μm) dispersed over the matrix. For Y-free or less alloy,the plasticity dropped sharply after high temperature treatment,while the plasticity is retained for the alloys containing 0.41-0.73 wt-% Y treated below 1340℃,because the Y-containing particles can strongly prevent from grain growth,and dislocation annihilation, and trap impurities.If treatment temperature is higher than 1340℃,however,these actions will dis- appear owing to the melting of the particles.

Key words: Fe-Cr-AI-Y alloy, embrittlement, microstructure