原子尺度計算機模擬
(西北工業(yè)大學 材料科學與工程學院， 西安 710072)
摘 要: 采用微觀相場模型， 基于離散格點形式的微觀擴散方程和非平衡自由能函數(shù)，編制了三元Ni75AlxV25-x合金的原子層面計算機模擬程序。模擬發(fā)現(xiàn)： 低鋁含量Ni75AlxV25-x合金的θ相先于γ′相析出， 其沉淀機制為等成分有序化+失穩(wěn)分解； γ′相在θ相的相界處非經(jīng)典形核， 二者均先形成非化學計量比有序相， 之后向化學計量比有序相轉(zhuǎn)變。
關鍵字: 早期沉淀； 原子尺度； 計算機模擬
of Ni75AlxV75-x alloys with lower Al concentration
（School of Materials Science and Technology,
Northwestern Polytechnical University, Xi′an 710072, China）
Abstract: With the microscopic phase-field model, the atomic-scale computer simulation programs of the ternary Ni-based alloys were worked out based on the microscopic diffusion equation and nonequilibrium free energy. The results show that for Ni75AlxV25-x alloy with lower Al composition, θ ordered phase precipitates earlier than γ′ ordered phase does by congruent ordering and spinodal decomposition mechanism, and thus produces a nonstoicheometric θ single ordered phase. Then, the nonstoicheometric γ′ phase precipitates by a non-classical nucleation and growth mechanism at the APBS of θ phases.
Key words: early precipitation process; atomic-scale; computer simulation
