(1. 中南大學(xué) 冶金與環(huán)境學(xué)院，長(zhǎng)沙 410083；
2. 中南大學(xué) 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083；
3. 世泰科化工貿(mào)易(上海)有限公司，上海 200030)
摘 要: 采用蒙特卡羅方法模擬過飽和液相體系內(nèi)的析出-長(zhǎng)大行為，其中針對(duì)溶質(zhì)擴(kuò)散、溶質(zhì)析出以及顆粒溶解等微觀過程分別制定模擬規(guī)則，并在分析模擬數(shù)據(jù)時(shí)引入臨界晶核，考慮液相析出濃度與臨界形核尺寸之間的關(guān)聯(lián)性。模擬結(jié)果表明，隨著模擬時(shí)間延長(zhǎng)，液相濃度和過飽和度均呈現(xiàn)出急劇下降、緩慢下降、最后趨于平衡穩(wěn)定的變化趨勢(shì)。模擬溫度越低，則平衡濃度越低，達(dá)到平衡濃度所需時(shí)間越長(zhǎng)，并且在圖形模擬結(jié)果中形成更多、更小的溶質(zhì)格點(diǎn)聚集析出微區(qū)。在延長(zhǎng)模擬時(shí)間的過程中，會(huì)發(fā)生Ostwald熟化長(zhǎng)大，并且平均析出顆粒半徑呈拋物線增加，提高模擬溫度則會(huì)引起更快的析出長(zhǎng)大行為，各種模擬溫度下得到的顆粒長(zhǎng)大指數(shù)在0.320~0.332之間，不隨模擬溫度變化發(fā)生較大波動(dòng)。上述模擬結(jié)果與NiFe2O4-KCl熔鹽體系和SrMoO4過飽和溶液體系在降低溫度和延長(zhǎng)保溫時(shí)間過程中的實(shí)驗(yàn)現(xiàn)象以及在擴(kuò)散過程控制下的Ostwald熟化長(zhǎng)大理論較為吻合。
關(guān)鍵字: 過飽和液相；蒙特卡羅方法；模擬；析出；長(zhǎng)大
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
3. H.C. Starck Trading(Shanghai) Co., Ltd., Shanghai 200030, China）
Abstract:The precipitation-growth progress in the supersaturated liquid was simulated by the Monte Carlo method. The simulation rules were established to simulate the micro-processes of solute diffusion, solute precipitation, and particle dissolution. The critical nucleus and the relationship between the critical nucleus size and liquid concentration were considered for analyzing the simulation data. The results show that during prolonging the simulation time, the liquid concentration and supersaturation ratio show rapid decrease, and slow decrease up to equilibrium sequentially. With decreasing simulation temperature, the equilibrium concentration decreases and the time to attain equilibrium becomes longer, and the solute lattices precipitate to form more smaller aggregations in the graphic results. Ostwald ripening growth occurs by prolonging the simulation time, in which the average precipitated particle radius increases parabolically. This growth is promoted by raising the simulation temperature. The particle growth exponents of 0.320-0.332 have only a tiny fluctuation when changing the simulation temperature. The simulation results are consistent with the temperature-decreasing and time-prolonging experiments of NiFe2O4-KCl molten salt system and SrMoO4 supersaturated solution, and the Ostwald ripening theory based on the diffusion-controlled kinetics.
Key words: supersaturated liquid; Monte Carlo method; simulation; precipitation; growth
