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采用微观相场动力学模型研究不同温度下Ni_(75)Al_(14)Mo_(11)合金的早期沉淀过程,研究合金的微观结构、Ll_0相的析出时间以及3种原子的占位概率。结果表明:沉淀过程中析出Ll_0非化学计量比有序相,Ll_0相有Ⅰ型和Ⅱ型2种结构,随着温度的增加,Ll_0相析出的时间提前。在沉淀的过程,Ⅱ型Ll_0结构的析出时间比Ⅰ型Ll_0结构的析出时间早。温度升高缩短了Ll_0相的形成时间,使Ll0相有序度更高;温度越低,Ll_0相向L1_2相的转变时间越短。Al原子和Mo原子占据γ位,Ni原子占据α位和β位,在同样的温度和格点下,Al原子的占位几率大于Mo原子的占位几率。Ni、Al和Mo_3种原子构成复合Ll_2相。
The microstructure of Ni_ (75) Al_ (14) Mo_ (11) alloy at different temperatures was studied by microscopic phase field kinetics model. The microstructure, the precipitation time of L_0 phase and the occupancy probability of three kinds of atoms were investigated. The results show that there are two kinds of structures, Ll_0 non-stoichiometric ordered phase and Ll_0 phase, precipitated in the precipitation process. With the increase of temperature, the precipitation time of Ll_0 phase is advanced. During the precipitation process, the type Ⅱ Ll_0 structure precipitates earlier than the type Ⅰ Ll_0 structure. The increase of temperature shortens the formation time of Ll_0 phase and makes Ll0 phase order higher. The lower the temperature, the shorter the transition time of Ll_0 phase to L1_2 phase. Al atom and Mo atom occupy γ position, and Ni atom occupies α and β positions. At the same temperature and lattice point, the probability of occupying Al atoms is greater than that of Mo atoms. Ni, Al and Mo_3 atoms constitute the composite Ll_2 phase.