摘要
The effect of rare-earth cerium on impurity P-induced embrittlement for an advanced SA508Gr.4N reactor pressure vessels steel is investigated by virtue of microstructural characterization,Auger electron spectroscopy(AES),and spin-polarized density functional theory(DFT)calculations.The ductile-to-brittle transition temperatures(DBTTs)are evaluated by Charpy impact testing,and grain boundary segregation(GBS)of P is quantified by AES.Trace addition of Ce can effectively reduce GBS level of P,thereby substantially decreasing the embrittlement induced by P.A linear correlation between DBTT(℃)and GBS level of P(Cp,at.%)is observed for both undoped and Ce-doped samples,being expressed as DBTT=13.13C_(p)-335.70(undoped)and DBTT=12.67C_(p)-350.78(Ce-doped).In the absence of GBS of P,the incorporation of Ce appears to play a pivotal role in augmenting the intrinsic toughness.These results imply that the impact of Ce on impurity P-induced embrittlement may be attributed to a combination of increasing the intrinsic toughness and lowering GBS of P.DFT calculations indicate that there is a negligible interaction between Ce and P in the ternary alloy,and thus GBS of P and Ce is mainly site-competitive.
基金
supported by the China Postdoctoral Science Foundation(No.2023M740973)
the Shenzhen Polytechnic University Research Fund,China(No.6023310017K)
the National Natural Science Foundation of China(Nos.52071088 and 51871064).
