界面穩(wěn)定性和形態(tài)的影響
(上海大學(xué) 材料科學(xué)與工程學(xué)院，上海 200072)
摘 要: 研究縱向穩(wěn)恒強(qiáng)磁場(chǎng)在定向凝固Al-0.85%Cu(質(zhì)量分?jǐn)?shù))合金平面晶−胞晶轉(zhuǎn)變過(guò)程中，對(duì)界面失穩(wěn)程度及胞晶形貌的影響。結(jié)果表明：隨著磁場(chǎng)強(qiáng)度的增加，界面失穩(wěn)程度先變小后變大，最后又變小；磁場(chǎng)強(qiáng)度為1 T時(shí)，界面失穩(wěn)程度最大，胞晶間距先減小后增大；磁場(chǎng)強(qiáng)度為4 T時(shí)，胞晶間距達(dá)到最小值；同時(shí)，磁場(chǎng)也使得胞晶形貌變得不規(guī)則。采用磁阻尼效應(yīng)和熱電磁對(duì)流(TEMC)相互競(jìng)爭(zhēng)的機(jī)制來(lái)解釋相關(guān)現(xiàn)象。
關(guān)鍵字: Al-0.85%Cu；定向凝固；強(qiáng)磁場(chǎng)；界面穩(wěn)定性；磁阻尼；熱電磁對(duì)流
（School of Material Science and Engineering, Shanghai University, Shanghai 200072, China）
Abstract:The effect of steady high longitudinal magnetic field on the interface stability and cellular morphology of Al-0.85%Cu (mass fraction) alloys was studied. The results show that the degree of interface stability changes from high to low and then to high again, at last from high to low with increasing the magnetic field intensity. When the strength of the magnetic field is 1 T, the instable interface is the most obvious. With increasing the strength of the magnetic field, the cellular spacing decreases firstly, reaches its least value at 4 T magnetic field, and then increases. At the same time, the cellular morphology changes to irregular. The experimental phenomena were analyzed according to competition of convection damping effect and thermo-electromagnetic convection effect with the magnetic field.
Key words: Al-Cu alloy; directional solidification; high magnetic field; interface stability; magneto-hydrodynamic effect; thermoelectro-magnetic convection
