Ni75Al_xV_25-x合金中异相界面成分演化的微观相场模拟

张明义^{1, 2}，杨  坤¹，陈  铮¹，王永欣¹，张嘉振²

(1. 西北工业大学 凝固技术国家重点实验室，西安 710072；
2. 中国商用飞机有限责任公司 北京民用飞机技术研究中心，北京 100083)

摘 要：采用微观相场模型研究界面原子结构和相变方向对Ni₇₅Al_xV_25-x合金中异相间有序畴界和有序/无序相界成分演化的影响。结果表明：在异相间有序畴界处，V在有序畴界的DO₂₂相一侧贫化，在有序畴界的L1₂相一侧偏聚；Al则在有序畴界的DO₂₂相一侧偏聚，在有序畴界的L1₂相一侧贫化。Ni在异相间可迁移有序畴界处的成分受相变方向和界面结构的影响。在DO₂₂相与无序相之间形成的相界处，Al和Ni偏聚，V则贫化；在L1₂相与无序相之间形成的相界处，Al和Ni贫化，V则偏聚。由于溶质拖拽效应，合金元素在有序畴界处的偏聚和贫化倾向不随有序畴界迁移改变，但程度变化。

关键词：Ni₇₅Al_xV_25?x合金；微观相场；有序畴界；有序/无序相界；成分偏聚

Microscopic phase-field simulation of composition evolution of heterointerfaces in Ni75Al_xV_25-x alloys

ZHANG Ming-yi^{1, 2}, YANG Kun¹, CHEN Zheng¹, WANG Yong-xin¹, ZHANG Jia-zhen²

(1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China;
2. Beijing Aeronautical Science & Technology Research Institute,
Commer)

Abstract:Microscopic phase-field model was used to study the effect of atomic structure of interfaces and phase transformation direction on the composition evolution of heterointerfaces (including ordered domain interfaces formed between L1₂ and DO₂₂ phases and order-disordered interfaces) in Ni₇₅Al_xV_25-x alloys. The results demonstrate that V depletes at the DO₂₂ side and segregates at the L1₂ side, and Al segregates at the DO₂₂ side and depletes at the L1₂ side of ordered domain interfaces formed between L1₂ and DO₂₂ phases during the phase transformation L1₂ DO₂₂. The composition of Ni at the ordered domain interfaces is affected by the phase transformation and atomic structure of interfaces. During the phase transformation L1₂→DO₂₂, Ni segregates at the interfaces which can migrate during the phase transformation. While at the interfaces (002)_D//(001)_L, Ni segregates at the L1₂ side and depletes at the DO₂₂ side, which is the same as the ordered domain interfaces formed between L1₂ and DO₂₂ phases during the phase transformation DO₂₂→L1₂. At the interface formed between DO₂₂ and disordered phase, Ni and Al segregate and V depletes. However, at the interface formed between L1₂ and disordered phase, Ni and Al deplete and V segregates. The tendency of segregation or depletion of alloy elements is unchanged with the ordered domain interface because of the solute drag effect, but the degree of segregation or depletion of alloy elements is changed.

Key words:Ni₇₅Al_xV_25?x alloys; microscopic phase-field; ordered domain interface; order-disordered interface; solute segregation