【摘要】 基于三元体系的离散格点的微观相场模型,模拟研究温度1123K时三元合金Ni-Cr-Al有序化早期过程,通过研究沉淀过程原子图像和序参数曲线的演化,发现低饱和度合金Ni-15at.%Cr-10.5at.%Al沉淀机制为非经典形核长大,沉淀过程包括D022有序相的形核长大,L12有序相的形核和D022有序相向L12有序相的转化3个阶段。由于Cr原子替代Al原子位置,在L12有序相内两种原子占位几率接近,形成Ni3(CrxAl1-x)结构的L12有序相,并且与D022有序相共存。高饱和度合金沉淀机制为等成分有序化和失稳分解混合机制,并且有序化和簇聚过程比低饱和度合金提前。更多还原

【Abstract】 The aging behavior of Ni-Cr-Al ternary alloy are studied at temperature 1123 K, the early ordering process are simulated at atomic-scale with microscopic phase-field model. Precipitation mechanism of low supersaturated alloy Ni-15at.%Cr-10.5at.%Al is non-classical nucleation and growth, the precipitation process include three stages, i.e. the nucleation and growth of D022 ordering phase, nucleation of L12 ordering phase and transmit of L12 ordering phase from D022 ordering phase. The occupation possibilities of Al and Cr in L12 ordering phase are similar because of substitution behavior of Cr atom, Ni3(CrxAl1-x) structure are formed and coexist with D022 ordering phase. high supersaturated alloys show the congruent ordering and spinodal decomposition mechanism and the process of the ordering and clustering are precedent to low supersaturated alloys.更多还原