( 1. 東南大學(xué) 材料科學(xué)與工程系, 南京 210018；
2. 鹽城工學(xué)院材料科學(xué)與工程系, 鹽城 224002；
3. 南京工程學(xué)院 材料科學(xué)與工程系, 南京 210023)
摘 要: 研究了Al-Sr變質(zhì)劑和鋯復(fù)合鹽細(xì)化劑對(duì)高近共晶Al-Si合金宏觀/微觀組織的影響。 結(jié)果表明： 單一Al-Sr變質(zhì)劑的加入， 不僅改變了共晶硅的形貌，同時(shí)對(duì)合金的組織也有較明顯的細(xì)化作用。 這可能是由于鍶的加入， 改變了液態(tài)金屬的結(jié)構(gòu)， 導(dǎo)致枝晶尖端前沿生長(zhǎng)過(guò)冷度增加， 降低了枝晶/α/(Al)固液界面能。 當(dāng)Al-Sr變質(zhì)劑和鋯復(fù)合鹽細(xì)化劑共同作用時(shí)， 隨著熔體中鋯含量的增加，鑄錠的晶粒度顯著減小， 當(dāng)熔體的鋯含量超過(guò)0.35%， 可獲得細(xì)小、 分布均勻的等軸晶， 其宏觀晶粒尺寸為100~120μm。 與Al-Zr中間合金相比， 無(wú)論是細(xì)化效果還是抗衰退的能力都優(yōu)于中間合金。
關(guān)鍵字: Al-Si合金; 變質(zhì); 晶粒細(xì)化; 宏觀/微觀組織
LIU Bing-yi3, SUN Guo-xiong2
（ 1. Department of Materials Science and Engineering,Southeast University,
Nanjing 210018, China;
2. Department of Materials Science and Engineering,
Yancheng Institute of Technology,
Yancheng 224002, China;
3. Department of Materials Engineering,
Nanjing Institute of technology,
Nanjing 230013, China）
Abstract: The influence of Al-Sr modifier and Zr compound salt on marco/micro structure of near-hypoeutectic Al-Si alloys was investigated. Only the addition of Sr into Al-Si alloys could result in transition of eutectic silicon from coarse plate-like or acicular to fine fibrous, at the same time it had also a better refinement to the structure of alloys. The present of Sr in Al-Si alloys causes the changes of structures of liquid metals, and leads to the decreases of the solid-liquid interfacial energy of dendrite α(Al) and increases of the growth undercooling of dendrite tips. The combined addition of Al-Sr and Zr compound salt, with increaseing the Zr content, the grain size decreases obviously. Finer and evenly equiaxed dendrite α(Al) is attained with addition of 0.35% Zr, and the size of macrostructure grain is about 100-120μm. The Zr in compound salt forms into the Al-Si alloys melt, compared to Al-Zr master alloys, the ability of grain refinement and resistant fading are better than those of Al-Zr master alloys.
Key words: Al-Si alloys; modification; grain refinement; macro/micro structure
