(1. 哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，哈爾濱 150001；
2. 中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083)
摘 要: 選取成分為Al-5.17Cu-2.63Si(合金A)、Al-4.29Cu-1.09Mg(合金B(yǎng))和Al-2.09Si-1.66Mg(合金C)三元鋁合金，分別進(jìn)行不同冷速下的凝固實(shí)驗(yàn)。對比研究不同凝固速率下得到的共晶相形貌與含量在接近各合金體系三元共晶溫度下熱處理前后的變化行為。結(jié)果表明：同一合金冷速越慢，得到的原始組織二次枝晶間距越大，合金A的石墨型、砂型、保溫型冷卻組織的二次枝晶間距分別為24.17、63.32和99.88 μm，合金B(yǎng)的二次枝晶間距分別為24.35、82.78和139.42 μm。均勻化熱處理的熱擴(kuò)散過程可以明顯地溶解非平衡共晶相，由于原始組織的尺度不同，共晶相所處的溶解階段與溶解程度不同。合金A的石墨型、砂型、保溫型組織熱處理后與熱處理前的共晶相含量比值分別為0.44、0.49和0.68，合金B(yǎng)的共晶相含量比值分別為0.084、0.30和0.38。
關(guān)鍵字: 凝固速率；共晶相；均勻化處理；三元Al合金
eutectic phases of Al alloys with different cooling rates
（1. School of Materials Science and Technology, Harbin Institute of Technology, Harbin 150001, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The solidification experiment with different solidification rates was carried out on three ternary alloys of Al-5.17Cu-2.63Si (alloy A), Al-4.29Cu-1.09Mg (alloy B) and Al-2.09Si-1.66Mg (alloy C). The influence of heat treatment on morphology and quantity of the non-equilibrium eutectic phases at the temperature close to the ternary eutectic point was investigated. The results show that the second dendrite space increases with decreasing the solidification rate. The secondary dendrite spacing of alloy A is 24.17 μm for the graphite mould, 63.32 μm for the sand mould, and 99.88 μm for the insulated mould, respectively, and the corresponding values of alloy B are 24.35, 82.78 and 139.42 μm. The nonequilibrium eutectic phases can be dissolved in the diffusion process during the heat treatment process. And the quantity of the dissolved eutectic phases depends on the initial microstructure. For alloy A the ratio of eutectic phase volume fraction after heat treatment to that before heat treatment are 0.44, 0.49 and 0.68, for the initial microstructure of graphite mould, sand mould and insulated mould, respectively, and the corresponding values of alloy B are 0.084, 0.30 and 0.38.
Key words: cooling rates; eutectic phases; granulation process; ternary Al alloys
