(1. 常州大學(xué) 材料科學(xué)與工程學(xué)院，常州 213164；
2. 常州大學(xué) 先進(jìn)金屬材料常州市重點(diǎn)實(shí)驗(yàn)室，常州 213164；
3. 三一重工股份有限公司，長沙 410100)
摘 要: 將Al-21%Si(質(zhì)量分?jǐn)?shù))合金在750~1 200 ℃分別重熔保溫20、40、60、80、100和120 min后銅模快冷及重熔保溫120 min后空冷，采用光學(xué)顯微鏡觀察分析合金中初晶硅形態(tài)與尺寸的變化，對Al-21%Si合金中的初晶硅的溶解動力學(xué)進(jìn)行分析。結(jié)果表明：過熱溫度越高，初晶硅尺寸越細(xì)小。在銅模快凝條件下，在750和850 ℃重熔時，保溫時間對初晶硅顆粒尺寸的影響較大；在950~1 200 ℃重熔時，保溫時間對初晶硅顆粒尺寸基本沒有影響。當(dāng)合金空冷時，即使過熱溫度足夠高也不能獲得細(xì)小的初晶硅組織，較高的過熱溫度和較快的冷卻速度有利于消除過共晶鋁硅合金中粗大初晶硅的遺傳現(xiàn)象和獲得細(xì)小的初晶硅。短時重熔實(shí)驗(yàn)和溶解動力學(xué)分析表明，當(dāng)合金在1 200 ℃重熔并保溫7~10 min后就可以使Al-21%Si合金中的初晶硅基本溶解。當(dāng)重熔溫度為950 ℃時，需要保溫1.4~1.7 h才能使初晶硅得到溶解。
關(guān)鍵字: 初晶硅；組織遺傳；溶解動力學(xué)；過熱溫度；快速凝固
（1. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
2. Key Laboratory of Advanced Metal Materials of Changzhou City, Changzhou University, Changzhou 213164, China;
3. Sany Heavy Industry Co., Ltd., Changsha 410100, China）
Abstract:The Al-21%Si alloy was rapidly cooled in copper mould after being overheated at 750−1 200 ℃ for 20, 40, 60, 80, 100 and 120 min, respectively. It was also dry quenched after being overheated at 750−1 200 ℃ for 120 min. The changes of the morphology and particle size of primary Si were analyzed with optical microscopy. The solution kinetic of primary Si in Al-21%Si melt was analyzed. The results show that the particle size of primary Si gradually decreases with the increase of overheating temperature. The effect of holding time on the particle size of primary Si is obvious as remelted at 750 and 850 ℃, and that is little as remelted at 950−1 200 ℃, when the alloy is cooled in copper mould. Fine primary Si microstructure cannot be obtained when the alloy is dry quenched even if the overheating temperature is quite high. High overheating temperature and rapid solidification are beneficial to eliminate the heredity of coarse primary Si in hypereutectic Al-Si alloy and to obtain the fine primary Si. Short-time remelt experiments and solution kinetic analysis indicate that the primary Si in Al-21%Si alloy can be mostly dissolved after the alloy is remelted at 1 200 ℃ for 7−10 min. When the remelt temperature is 950 ℃, the holding time of 1.4−1.7 h is needed for the solution of primary Si.
Key words: primary Si; structural heredity; solution kinetic; overheating temperature; rapid solidification
