摘要
采用微观相场动力学模型,在原子层面上研究Ni75AlxV25-x合金中γ′相和θ相的沉淀过程及微观结构演化。模拟实验结果表明,Al浓度对沉淀序列具有重要的影响。低Al浓度合金中,先析出θ(Ni3V)有序相,随后析出γ′(Ni3Al)有序相;中Al浓度合金中,θ有序相及γ′有序相几乎同时析出;高Al浓度合金中,γ′有序相先析出,θ有序相随后析出。沉淀过程中,θ有序相和γ′有序相长大和粗化过程中存在竞争关系,无论先析出哪种相,θ有序相在粗化的竞争过程中占有优势。因此,沉淀最后形成择优取向的显微组织。
With microscopic phase-field kinetic model, atomic-scale computer simulation program for the precipitation sequence and microstructure evolution of the ordered intermetallic compound γ' and θ in ternary Ni75AlxV25-x alloy were studied. The simulation results show that Al concentration has important effects on the precipitation sequence. When Al concentration in Ni75AlxV25-x alloy is low, 0(Ni3V) ordered phase will be firstly precipitated, followed by γ'(Ni3Al) ordered phase. With Al concentration increasing, θ and γ' ordered phases are simultaneously precipitated. With A1 concentration further increasing, γ' ordered phase is firstly precipitated, followed by θ ordered phase. There is a competition relationship between θ and γ' ordered phases during growth and coarsening process. No matter which first precipitates, θ ordered phase always occupies advantage in the competition process of coarsening, thus, the microstructure with preferred orientation is formed.
基金
Projects(51174168,51274167)supported by the National Natural Science Foundation of China
Project(2014JM7261)supported by the Natural Science Basic Research Plan in Shaanxi Province of China
Project(B08040)supported by "111" Project,China