三维原子探针表征淬回火Cr-Mo-V-Ni中合金钢的元素分布

摘要

将Cr-Mo-V-Ni中合金钢在1030℃奥氏体化保温0.5 h后油淬,在600℃回火2次,每次2 h.结合光学显微镜(OM)和扫描电子显微镜(SEM),采用三维原子探针(3DAP)技术分析了淬火态和回火态各元素原子的三维空间分布以及碳化物内部和碳化物/基体界面处元素分布和成分变化.结果表明,淬火试样中C原子由于自回火和短程扩散出现了较为明显的片状偏聚,而其他合金原子Cr、Mn、Mo、Si、V和Ni基本分布均匀;回火试样中C、Cr、Mo和V发生共偏聚形成厚度约10 nm的合金碳化物M23 C6,Si原子形成一层薄薄的偏聚层包裹着M23 C6,而Ni又包裹着Si原子而偏聚于最外层.%Three dimensional atom probe (3DAP ) combined with optical microstructure (OM ) and scanning electron microscopy (SEM ) were applied to characterize the spatial distributions of carbon atom and alloy elements concentration of tested steel tempered twice at 600 ℃ for 2 h after quenched at 1030 ℃ holding 0 .5 h ,respectively .Simultaneously ,the elements segregation in carbide and at carbide/matrix interface was also analyzed .The results indicated that the alloying elements Cr ,Mn , Mo ,Si ,V and Ni atoms in the as-quenched specimen were almost no segregation ,and element C was obviously sheet-like segregation attributed to auto-tempering and short-range diffusion of C atom .Co-segregation of C ,Cr ,Mo and V atoms occurred to form the M23C6 alloy carbide with a thickness about 10 nm in as-tempered specimen .The M23C6 carbide was wrapped by Si atom with a thin segregation layer ,while the Si atom is surrounded by the Ni atom segregated at the outermost .