Effect of Ce on microstructure evolution of oxide scale for CLAM steel exposed to LBE containing 10−6 wt% oxygen at 500 ℃

•Ce made the shape of magnetite island change from roughly circular to slat-like.•The magnetite pellets of both CLAM and Ce-CLAM specimens had a growth trend from small to large.•Ce enhanced the adhesion, continuity and integrity of oxide scale, and delayed the evolution of magnetite.•The mechanism model of Ce effect on the evolution of magnetite and the scale growth model of the two kinds of specimens were proposed.