【摘要】 在１０２３～１３７３Ｋ的初始温度范围和０．０５～２６８．９１Ｋ／ｓ的冷速范围内，用俄歇剖层分析确定了含硼Ｎｉ_３Ａｌ合金中硼的非平衡晶界偏聚行为。基于由空位在晶界湮灭所产生的体系自由能下降驱动可动的溶质－空位复合体向晶界迁移、从而产生溶质非平衡晶界偏聚的模型，导出了定量描述非平衡偏聚行为的解析表达式。理论计算结果与硼非平衡偏聚的试验数据相符。通过模拟实测确定Ｎｉ_３Ａｌ－Ｂ合金中硼及硼－空位复合体的扩散系数分别为：Ｄ＝１×１０￣（－６）ｅｘｐ［－１．９６（ｅＶ）／ｋＴ］和Ｄ_Ｐ（Ｂ）＝１×１０￣（－）４ｅｘｐ［－１．９６（ｅＶ）／ｋＴ］（ｍ￣２／ｓ）；硼－空位复合体的结合能为Ｅ₍ｂ（Ｂ）＝０．５ｅＶ。更多还原

【Abstract】 The non-equilibrium grain boundary segregation of boron in Ni₃Al-B alloys was determined by Auger electron spectroscopy（AES） in conjunction with ion sputtering in a cooling rate range 0. 05-268. 91K/s for three temperatures 1023, 1223 and 1373 K. On the other hand, based on the concept that mobile solute-vacancy complexes diffusing to grain boundaries（vacancy sinks） was responsible for the non-equilibrium grain boundary segregation of solute atoms in alloys, an analytical expression for the segregation behavior was put forward in the present study. The driving force for the segregation was the change in free energy of the system caused by the annihilation of vacancies at grain boundaries during cooling from an initial temperature. The theoretical simulations fitted the data of non-equilibrium segregation of boron well. The diffusion coefficients for boron atoms and boron-vacancy complexes in Ni₃Al-B alloys were determined to be D=1×10￣（-6）exp [-1.96 （eV）/kT] and D_P（B）=1×10￣（-4）exp [-1. 96 （eV）/kT] （m￣2/s）, respectively, and the binding energy of the boronvacancy complexes was estimated to be E_b（B） =0.5eV.更多还原