利用APT研究铁素体时效钢中富Cu相和碳化物的偏析行为
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摘要
铁素体时效钢样品经过880℃水淬、660℃调质处理,然后400℃时效4000 h后,利用三维原子探针层析技术(APT)研究了时效钢中晶界和基体中富Cu析出相和碳化物的偏析行为。结果表明:分析区域中Mn、Ni、Mo、C和Cu元素更容易在晶界处偏聚,形成富Cu团簇和碳化物,晶界处的纳米富Cu相为短棒状,其尺寸大小约为6 nm,团簇中的Cu原子含量为40at%。基体中的纳米团簇近似为球状,其尺寸和团簇中的Cu原子的数量密度都比晶界处小。在晶界处析出的富Cu团簇在碳化物之间,形成一种"夹层结构"。此外,富Cu团簇内部有Mn和Ni原子的偏聚,促进富Cu相的析出。
The samples of ferrite aging steel were quenched at 880 ℃, tempered at 660 ℃, then aged at 400 ℃ for 4000 h. The segregation behavior of rich Cu precipitates and carbides in aging steel were studied by using three-dimensional atomic probe tomography(APT) technique. The results show that, the elements of Mn, Ni, Mo, C and Cu in the analytical region tend to converge at grain boundaries more easily, forming rich Cu clusters and carbides. The nanocrystalline rich Cu phase at grain boundary is short rod shape, and its size is about 6 nm. The Cu atom content in the cluster is 40 at%. The nanoclusters in the matrix are spherical, the size and the number density of Cu atoms in the clusters is smaller than that at the grain boundaries,and a "sandwich structure" is formed between the rich Cu clusters and carbides precipitated at the grain boundaries. In addition, the segregation of Mn and Ni atoms in the rich Cu cluster promotes the precipitation of the rich Cu phase.
The samples of ferrite aging steel were quenched at 880 ℃, tempered at 660 ℃, then aged at 400 ℃ for 4000 h. The segregation behavior of rich Cu precipitates and carbides in aging steel were studied by using three-dimensional atomic probe tomography(APT) technique. The results show that, the elements of Mn, Ni, Mo, C and Cu in the analytical region tend to converge at grain boundaries more easily, forming rich Cu clusters and carbides. The nanocrystalline rich Cu phase at grain boundary is short rod shape, and its size is about 6 nm. The Cu atom content in the cluster is 40 at%. The nanoclusters in the matrix are spherical, the size and the number density of Cu atoms in the clusters is smaller than that at the grain boundaries,and a "sandwich structure" is formed between the rich Cu clusters and carbides precipitated at the grain boundaries. In addition, the segregation of Mn and Ni atoms in the rich Cu cluster promotes the precipitation of the rich Cu phase.
引文
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[17]Zhang C,Enomo to M.Study of the influence of alloying elements on Cu precipitation in steel by non-classical nucleation theory[J].Acta Materialia,2006,54(16):4183-4191.
[2]Kuleshova E A,Gurovich B A,Shtrombakh Y I,et al.Microstructural behavior of VVER-440 reactor pressure vessel steels under irradiation to neutron fluences beyond the design operation period[J].Journal of Nuclear Materials,2005,342(1/3):77-89.
[3]Odette G R.On the dominant mechanism of irradiation embrittlement of reactor pressure vessel steels[J].Scripta Metallurgica,1983,17(10):1183-1188.
[4]Akamatsu M,Van Duysen J C,Pareige P,et al.Experimental evidence of several contributions to the radiation damage in ferritic alloys[J].Journal of Nuclear Materials,1995,225(2):192-195.
[5]杜涛,陈军,袁诚.时效温度对17-4PH沉淀硬化不锈钢析出行为和硬化效果的影响[J].热加工工艺,2015,44(4):233-235.
[6]Edmondson P D,Parish C M,Nanstad R K.Using complimentary microscopy methods to examine Ni-Mn-Si-precipitates in highly-irradiated reactor pressure vessel steels[J].Acta Materialia,2017,134(1):31-39.
[7]Auger P,Pareige P,Welzel S,et al.Synthesis of atom probe experiments on irradiation-induced solute segregation in French ferritic pressure vessel steels[J].Journal of Nuclear Materials,2000,280(3):331-344.
[8]Miller M K,Wirth B D,Odette G R.Precipitation in neutron-irradiated Fe-Cu and Fe-Cu-Mn model alloys:a comparison of APT and SANS data[J].Materials Science&Engineering A,2003,353(1/2):133-139.
[9]Miller M K.Atom probe tomography analysis at the atomic level[M].London:John Wiley&Sons,Inc.,2015.
[10]周邦新,刘文庆.三维原子探针及其在材料科学研究中的应用[J].材料科学与技术,2007,15(3):405-408.
[11]周邦新,王均安,刘庆东,等.Ni对RPV模拟钢中富Cu原子团簇析出的影响[J].中国材料进展,2011,30(5):1-6.
[12]Cerezo A,Hirosawa S,Rozdilsky I,et al.Combined atomic-scale modelling and experimental studies of nucleation in the solid state[J].Philos Trans A Math Phys Eng Sci,2003,361(1804):463-476.
[13]Isheim D,Kolli R P,Fine M E,et al.An atom-probe tomographic study of the temporal evolution of the nanostructure of Fe-Cu based high-strength low-carbon steels[J].Scripta Materialia,2006,55(1):35-40.
[14]Kolli R P,Mao Z,Seidman D N,et al.Identification of a Ni0.5(Al0.5-xMnx)B2phase at the heterophase interfaces of Cu-rich precipitates in anα-Fe matrix[J].Applied Physics Letters,2007,91(24):35.
[15]徐洲,赵连成.金属固态相变原理[M].北京:科学出版社,2004.
[16]徐刚,蔡琳玲,冯柳.利用APT对RPV模拟钢中界面上原子偏聚特征的研究[J].金属学报,2012,48(7):789-796.
[17]Zhang C,Enomo to M.Study of the influence of alloying elements on Cu precipitation in steel by non-classical nucleation theory[J].Acta Materialia,2006,54(16):4183-4191.