Exploring atomic occupation of ternary alloy elements at L1₂-Ni₃Al sub-lattice

L1₂-Ni₃Al 亚晶格第三合金化元素原子占位研究

¹ Flying College, Shandong University of Aeronautics, Binzhou 256600, China
² School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China

Received: 24 March 2024

Abstract

The Ni₃Al phase of L1₂ crystal lattice is the most important strengthening phase for nickel-base super-alloy of an aero-engine. The configuration of atomic occupation of alloy elements at the L1₂-Ni₃Al sub-lattice plays a key role in its serving properties in the thermal-mechanic condition. Through establishing the phase-field model of a ternary alloy system and solving the micro-diffusion dynamic functions, the spatial-temporal information on the atomic occupation of different L1₂-Ni₃Al sub-lattices is tracked, the occupation capability of ternary alloy elements is assessed and the atomic density distribution at single-lattice points is obtained. The atomic occupation of Ni-Al-V and Ni-Al-Cr precipitation phases in the L1₂-Ni₃Al sub-lattice after the phase transformation path of FCC→L1₂+D0₂₂ is studied. The results show that through the time-related order process, the atomic occupation removes the competitive growth in the homogeneous or heterogeneous phase in the early phase transformation and the random fluctuation that interface migration causes to the sub-lattices. The Ni₃Al phase is in fact a compound metal alloy phase. The antisite and substitution site are the functions of the binary solute ratio. The addition of Cr and V has an obvious difference in affecting the antisite and substitution site in different sub-lattices, which is related to sub-lattice type, defect type and alloy element type.

摘要

L1₂晶格结构Ni₃Al相为航空发动机镍基高温合金最重要的强化相, 其亚晶格上合金体系组成元素的原子占位配置对热-力环境下服役性能起决定性作用。针对L1₂-Ni₃Al内不同亚晶格上原子占位的时-空信息追踪与第三合金化元素的占位能力评估, 通过求解微观扩散动力学方程, 构建三元合金体系相场模型, 得到单晶格格点原子密度分布, 研究了经FCC→L1₂+D0₂₂相变路径后的Ni-Al-Cr与Ni-Al-V沉淀相L1₂-Ni₃Al中的原子占位。结果表明, 平衡期占位通过与时间相关的有序化过程消除相变早期的同相/异相竞争生长, 以及界面迁移对亚晶格上原子占位带来的随机波动性影响; Ni-Al-Cr与Ni-Al-V中Ni₃Al相均为复合金属间化合物相, Ni、Al亚晶格上反位、替位为双溶质比的函数; Cr、V添加对Ni₃Al中不同亚晶格的反位、替位的影响具有明显差异性, 与晶格类型、缺陷类型以及组元类型相关。