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采用变温机械搅拌方法制备Al Si7Mg合金半固态浆料,研究了冷却速度、剪切速率对浆料组织的影响,探讨了强制对流条件下半固态浆料中球状初生相的制备机理。结果表明:在强制对流机械搅拌、剪切速率40 s-1,冷却速度0.12~0.25℃/s以及剪切速率20~80 s-1、冷却速度0.12℃/s条件下制备出近球状组织的Al Si7Mg合金半固态浆料。增加剪切速率对浆料组织形貌影响不大,冷却速度是决定半固态浆料组织形貌的关键因素。强制对流下的合金熔体,在保证合金熔体温度场、溶质场均匀性和合适的冷却速度条件下,初生相就会以球状晶的特定生长方式生长,从而获得满足流变成形的半固态浆料组织。
The Al 7 Mg alloy semi-solid slurry was prepared by a variable temperature mechanical stirring method. The effects of cooling rate and shear rate on the microstructure of the slurry were investigated. The preparation mechanism of spherical primary phase in semi-solid slurry under forced convection was also discussed. The results showed that the near-spherical structure was prepared under forced convection mechanical stirring, shear rate of 40 s-1, cooling rate of 0.12 ~ 0.25 ℃ / s, shear rate of 20-80 s-1 and cooling rate of 0.12 ℃ / s Al Si7Mg alloy semi-solid slurry. Increasing the shear rate has little effect on the microstructure of the slurry, and the cooling rate is the key factor that determines the microstructure of the slurry. Forced convection under the alloy melt, to ensure that the alloy melt temperature field, solute field uniformity and the appropriate cooling rate conditions, the primary phase will grow in a spherical crystal specific growth to obtain to meet the rheological forming of the semi Solid slurry organization.