| The nuclear reactor with liquid metal as coolant has good neutrons,thermal hydraulics and safety characteristics.It has become one of the main candidate reactors for the fourth generation of advanced nuclear power system(fast reactor)and fusion reactor.However,during the operation of the reactor,liquid metal will corrode the structural materials of the reactor,resulting in the dissolution of the alloying elements in the structural materials,resulting in the decrease of its performance,thus affecting the service life of the structural materials.Oxide dispersion strengthened alloy(ODS alloy)has excellent resistance to irradiation and high temperature resistance.It is an important candidate structure material for fast reactor and fusion reactor.In this paper,8 kinds of with different alloy elements(Zr,Ti)added 15Cr-ODS alloy containing Al and without adding Al were prepared by means of mechanical alloying(MA)and hot isostatic pressing(HIP).After the high temperature corrosion test for 2000 h in liquid lead bismuth and liquid lithium lead,the micromorphology,composition and structure of the oxide layer on the surface of the alloy are analyzed by SEM,EDS,XRD and TEM.The following results have been obtained:(1)15Cr-ODS alloy YAl(without adding Ti and Zr),YAlZr(adding Zr),YAlTi(Ti)and YAlZrTi(at the same time adding Zr and Ti)all generated oxide layer in liquid lead bismuth,blocking the penetration of liquid lead and bismuth into the matrix,and the oxide layer was stratified.After the corrosion of YAl alloy,the oxidation layer is the thickest,about 17 ?m.Under the same conditions,the oxide layer of YAlZr alloy and YAlTi alloy is thinner(about 11?m),indicating that the corrosion resistance of the alloy is enhanced,and the oxide layer of YAlZrTi alloy is the thinnest,which is about 6?m.It is indicated that adding Zr,Ti and especially at the same time can effectively improve the corrosion resistance of ODS alloy in liquid lead bismuth.(2)The oxide production of YAl alloy and YAlZr alloy are two oxide layers,the inner oxide layer is spinel Fe(FexCr1-x)2O4 structure,the outer oxide layer is Fe3O4 and spinel Fe(FexCr1-x)2O4 hybrid structure.The oxide production of YAlTi alloy are three oxide layers,the inner layer is spinel structure Fe(FexCr1-x)2O4,the middle layer is Fe3O4 and spinel Fe(FexCr1-x)2O4 hybrid structure,the most external layer is Fe304.The oxide production of YAlZrTi alloy are two oxide layers,and the extremely thin inner oxide layer is spinel structure Fe(FexCr1-x)2O4,and the outer layer is Fe3O4.The structure of Fe-Cr spinel in the inner layer is more compact,which can effectively prevent the infiltration of liquid lead and bismuth,so that the ODS alloy has good corrosion resistance in liquid lead bismuth..(3)Al free 15Cr-ODS alloy Y(without adding Zr and Ti),YZr(adding Zr),YTi(adding Ti),YZrTi(adding Zr and Ti)in liquid lithium lead for 2000h,and then formed oxide layer.The oxide layer also appeared stratification.The oxide layer of Y alloy is the thickest,which is 65?m,and the oxide layer of YZr and YTi alloy is thinner,which is 25 ?m and 45 ?m,respectively.The oxide layer of YZrTi alloy is the thinnest,which is about 18?m.The results show that the addition of Zr and Ti,especially at the same time,can effectively improve the corrosion resistance of ODS alloy in liquid lithium lead.(4)The surface oxidation products of Al free ODS alloy with different alloying elements(Y,YZr,YTi and YZrTi)are similar in the liquid lithium lead environment,and the order from outside to inside is Fe2O3,Fe3O4,Fe-Cr spinel.It is shown that the addition of different alloy elements has little effect on the surface oxidation products of ODS alloy in liquid lithium lead,which mainly affects the thickness of the oxidation layer.The outer oxide Fe2O3 is not dense enough,which leads to the penetration of liquid lithium lead.The inner layer is dense,which can effectively block the penetration of lithium lead,which makes the ODS alloy has good corrosion resistance in liquid lithium lead. |
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