【摘要】 研究了AlSi6.5Cu2 .8Mg合金在固、液相区温度重熔时 ,固、液相转变 ,α晶体形貌演变的规律和α晶体长大的规律。试验结果表明 :半固态重熔时 ,α晶体的形态的演变过程按液相量和成份的变化以及α晶体的形态变化分为 3个阶段 :第一阶段为液相量的增加阶段 ;第二阶段为液相成份向平衡亚共晶成份转化阶段 ;第三阶段为液相达平衡亚共晶成份以后的阶段 ;在第一和第二阶段 ,α晶体以碰撞合并方式长大 ,第三阶段按Ostward方式长大。试验数据作统计分析知 :α晶体的直径d与时间的抛物线关系的幂指数是随重熔温度而变化的 ;573℃ ,578℃和 584℃对应的幂指数分别是 4 .0 0 4 ,2 .38和 1.84 ;幂指数主要受熔体中对流强度的影响。更多还原

【Abstract】 Processings of solid to liquid transformation and primary α structural evolution of AlSi6.5Cu2.8Mg alloy are investigated in semi-solid remelting condition.Results show that structural evolution of the alloy consists of three stages:liquid increasing stage,transforming stage of compostion of liquid from eutectic to hopy-eutectic,and implementation stage of hopy-eutectic composition of liquid,and α crystal grows in forms of collistion and coalescence in the first and second stages and in form of Ostard repening in the third stage.It is found from statistical analysis that power exponent in parabola function relation between α crystal diameter and remelting time changes with remelting temperatures,power exponents with respect to remelting temperatures of 573 ℃,578 ℃ and 584 ℃ are 4.004,2.380 and 1.840 respectively,and convection intensity in semi-solid melt is a main factor influence these exponents.更多还原