Al-20%Si合金凝固組織的影響
(1. 福州大學(xué) 材料科學(xué)與工程學(xué)院，福州350108；2. 福州大學(xué) 機(jī)械工程及自動(dòng)化學(xué)院，福州350108；
3. 福建工程學(xué)院 材料系，福州350108)
摘 要: 采用熔體溫度處理(包括熔體混合及過(guò)熱處理)工藝研究Al-20%Si(質(zhì)量分?jǐn)?shù))合金凝固組織，并結(jié)合化學(xué)變質(zhì)法進(jìn)一步細(xì)化初生硅相。結(jié)果表明，當(dāng)熔體經(jīng)混合后過(guò)熱至900 ℃時(shí)，初生硅的尺寸約為34 μm；添加變質(zhì)劑后再進(jìn)行熔體混合可以使Al-20%Si中的初生硅相進(jìn)一步細(xì)化，特別是在Al-10%Si和Al-30%Si中分別添加0.2%Al-5Ti-C-3Ce和0.4%Cu-10%P后，再進(jìn)行熔體過(guò)熱處理，合金中的初生硅呈小塊狀彌散分布，且尺寸在10 μm以下，材料基體呈現(xiàn)出典型的復(fù)合材料特征。熔體溫度處理與添加化學(xué)變質(zhì)劑方法對(duì)初生硅相有顯著的多重變質(zhì)細(xì)化作用；在熔體混合時(shí)α(Al)的重新熔化和熔體化學(xué)鍵的重組，增大了合金液在凝固時(shí)的過(guò)冷度，使初生硅相得到細(xì)化；對(duì)混合熔體再進(jìn)行過(guò)熱處理時(shí)，混合熔體中的Si相發(fā)生熔斷、增殖，從而使合金中初生硅相得到進(jìn)一步細(xì)化。添加細(xì)化劑或變質(zhì)劑會(huì)明顯增強(qiáng)熔體溫度處理對(duì)Al-Si合金中初生硅的細(xì)化效果。
關(guān)鍵字: 高硅鋁合金；熔體溫度處理；熔體混合；熔體過(guò)熱；變質(zhì)；細(xì)化
solidification microstructure of Al-20%Si alloy
HUANG Li-guang2, SONG Wei1, WU Hai-bin<
（1. College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China;
2. College of Mechanical Engineering, Fuzhou University, Fuzhou 350108, China;
3. Department of Materials Science, Fujian University of Technology, Fuzhou 350108, China）
Abstract:The microstructures of Al-20%Si (mass fraction) alloy prepared by melt thermal treatment (including the melt mixing and melt superheating) were studied combining with chemical metamorphism to further refine the primary silicon. The results show that, when the mixed melt is superheated to 900 ℃, the grain size of primary silicon is decreased to about 34 μm. And adding the modificator or refiner into the melt before melt mixing can further refine the primary silicon of Al-20%Si. Especially, when the Al-10%Si melt mixes with the Al-30%Si melt added 0.2%Al-5Ti-C-3Ce and 0.4%Cu-10P, respectively, then superheated the mixed melt, the primary silicon of Al-20%Si is well uniformly distributed in tiny blocklike with the grain size less than 10 μm, which makes the matrix of the alloy exhibit typical composite characteristic. The analysis shows that the melt thermal treatment and adding modificator or refiner at the same time have multiple modification effects on the primary silicon. The melt thermal treatment increases the supercooling degree during the solidification process of the alloys to refine or modify the primary silicon because of the re-melt of primary α(Al) and the recombination of chemical bond in Al-Si alloy as mixing the different melt together. And then superheating the mixing melt can make the pre-crystallized primary silicon split and proliferate, thus further refine or modify the primary silicon. And adding refiner or modificator can improve the refinement effect of the melt thermal treatment on the primary silicon of the Al-Si alloys.
Key words: hypereutectic Al-Si alloy; melt thermal treatment; melt mixing; melt-superheating; modification; refinement
