(1. 蘭州理工大學(xué) 甘肅省有色金屬新材料省部共建國家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050；
2. 蘭州理工大學(xué) 有色金屬合金省部共建教育部重點(diǎn)實(shí)驗(yàn)室，蘭州 730050)
摘 要: 采用液-液混合受控?cái)U(kuò)散凝固技術(shù)(CDS)制備過共晶Al-20%Si合金，研究高硅合金溫度對目標(biāo)合金組織中初生硅的影響及混合過程中初生硅細(xì)化的熱力學(xué)條件。結(jié)果表明：采用液-液混合制備過共晶鋁硅合金，可以細(xì)化初生硅，初生硅平均尺寸可達(dá)到37 μm；但隨著高硅合金溫度的升高，初生硅的平均尺寸增加，板條狀和五瓣星狀初生硅也增多，當(dāng)高硅溫度超過790 ℃時(shí)，初生硅細(xì)化效果喪失。分析得出，只有當(dāng)混合前兩種合金吉布斯自由能的加權(quán)平均值小于混合后目標(biāo)合金在液相線的吉布斯自由能( =-39.336 6 kJ)時(shí)，初生硅才能得到明顯的細(xì)化。
關(guān)鍵字: 過共晶Al-Si合金；液-液混合；受控?cái)U(kuò)散凝固(CDS)；初生硅相；熱力學(xué)
（1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Non-ferrous Metal Alloys, Ministry of Education,
Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:The hypereutectic Al-20%Si alloy was fabricated by liquid-liquid mixing of controlled diffusion solidification (CDS), and the effect of temperature of high silicon alloy on the microstructure of primary silicon phase and thermodynamic condition of primary silicon refinement in the mixing process were studied. The results show that the primary silicon can be refined obviously and the size of the primary silicon can reach 37 μm in the preparation of hypereutectic Al-20%Si alloy fabricated by liquid-liquid mixing. When the temperature of high silicon alloy increases, the primary phase size increases. When the high silicon temperature is over 790 ℃, the refinement effect of primary silicon is lost. Additionally, when the Gibbs free energy of the liquids prior to mixing is less than the Gibbs free energy of the resultant liquid at its liquidus temperature ( =-39.336 6 kJ), the primary silicon phase will be refined obviously.
Key words: hypereutectic Al-Si alloy; liquid-liquid mixing; controlled diffusion solidification (CDS); primary silicon; thermodynamic
