When the Nb con- tent exceeds 1.5 wt%,the eutectic NbC carbides on grain boundaries become lamellar and the amount of M_(23)C_6 carbides within grains decrease significan- tly,and therefore the creep rupture strength of the alloy decreases.

• 当 Nb 量进一步提高时,由于共晶 NbC 形成了片层状共晶团以及晶内 M_(23)C_6大量减少使蠕变断裂强度下降。