(1. 上海大學(xué) 材料科學(xué)與工程學(xué)院, 上海 200072;
2. 中北大學(xué) 機(jī)電工程系, 太原 030008)
摘 要: 以群體動力學(xué)模型為基礎(chǔ)， 在充分考慮合金的熱物性參數(shù)、 過飽和度以及第二相形核率變化的基礎(chǔ)上， 提出描述該合金快速凝固組織演變的數(shù)學(xué)模型， 并結(jié)合A390合金進(jìn)行計算。 結(jié)果表明: 隨著霧化合金液滴尺寸的減小， 平均冷卻速度增加， 而初生Si相長大時間減少， 所析出初生Si相的尺寸及體積分?jǐn)?shù)也不斷減小； 當(dāng)粉末尺寸減小到某一臨界值時， 初生Si相消失， 從而使不同尺寸粉末的微觀組織發(fā)生很大的變化。 計算結(jié)果與實驗結(jié)果吻合較好， 說明此提出的模型可以較好地預(yù)測過共晶Al-Si合金快速凝固組織的形成， 從而為進(jìn)一步研究高硅合金材料的組織演變奠定基礎(chǔ)。
關(guān)鍵字: 快速凝固； 霧化液滴； 微觀組織演變； 模擬； 群體動力學(xué)
（1. School of Material Science and Engineering, Shanghai University,
Shanghai 200072, China;
2. Department of Mechanical and Electronic Engineering, Zhongbei University, Taiyuan 030008, China）
Abstract: Based on both the population dynamics model and the continuous variety of thermo-physical parameters, supersaturation and nucleation rate, a model was developed to describe the microstructure evolution of hypereutectic Al-Si alloy during rapid solidification, and was solved for A390 alloy. The results show that, with the droplet size decreasing, the average quenching velocity increases and the growth time, size and volume fraction of primary Si decrease. The primary Si of powder particle is extinct under a critical size, which result in the different microstructures of various powder particles. The results of atomization experiments of hypereutectic Al-Si alloys show a good agreement with the theoretical calculations. The model can be used to predict satisfactorily the microstructures evolution of hypereutectic Al-Si alloys.
Key words: rapid solidification; atomized droplets; microstructure evolution; simulation; population dynamics
