(東北大學(xué) 材料電磁過(guò)程研究教育部重點(diǎn)實(shí)驗(yàn)室，沈陽(yáng) 110819)
摘 要: 為了了解電磁場(chǎng)對(duì)組織細(xì)化作用的機(jī)理，采用低頻電磁鑄造方法制備直徑200 mm Al-Zn-Mg-Cu-Zr合金鑄錠，并對(duì)鑄造過(guò)程中的溫度場(chǎng)進(jìn)行測(cè)量。結(jié)果表明：施加磁場(chǎng)產(chǎn)生的強(qiáng)制對(duì)流使得溫度場(chǎng)均勻且低于液相線約6 ℃。結(jié)晶器中熔體溫度場(chǎng)的變化顯著改變了熔體從開(kāi)始澆注到完全凝固的熱歷史，從而有效促進(jìn)了異質(zhì)形核，顯著減少晶核的重熔，使更多晶核能夠生存下來(lái)，并最終促進(jìn)形成均勻、細(xì)小的微觀組織。
關(guān)鍵字: Al-Zn-Mg-Cu-Zr合金；低頻電磁鑄造；溫度場(chǎng)；晶粒細(xì)化；細(xì)化機(jī)理
（Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education,
Northeastern University, Shenyang 110819, China）
Abstract:In order to understand the mechanism of grain refinement achieved by electromagnetic field, ingots of an Al-Zn-Mg-Cu-Zr alloy with diameter of 200 mm were cast and the temperature field was measured during the casting process. The results show that the electromagnetic field can induce the forced convection, leading to a quite uniform temperature field and a low temperature (6 ℃ bellow the liquidus). Therefore, the thermal history of the melt from pouring to being solidified is changed obviously, resulting in an enhanced heterogeneous nucleation and remarkable decrease of the remelting of the formed nuclei and the formation of fine and uniform spherical equiaxed microstructure.
Key words: Al-Zn-Mg-Cu-Zr alloy; low frequency electromagnetic casting; temperature field; grain refinement; refinement mechanism
