中文摘要：

采用自行研发的自孕育制浆技术制备AM60半固态浆料,利用冷室压铸机对浆料进行流变压铸成形试验,研究压射速度对铸件缺陷形成的影响。结果表明,当压射速度小于0.5m/s时,铸件充型不足;增大至2.0m/s后,铸件充型完整,但充型末端易出现冷隔缺陷;压射速度大于7.0m/s导致铸件出现严重飞边。显微组织分析表明,压射速度增大,铸件内微气孔增多且尺寸增大,铸件边缘液相偏析程度减小,同时内部夹杂增多,夹杂物尺寸较大;当压射速度小于1.0m/s时,初生相形貌发生粗化,液相中二次枝晶增多。因此,高压射速度能在一定程度上提高流变压铸件显微组织的均匀性,但同时使铸件气孔、夹杂缺陷增多,不利于提高半固态压铸件的力学性能。

英文摘要：

The semisolid slurry of AM60 alloy was prepared by self-inoculation method,and the cold chamber die casting machine was employed to form the semisolid slurry under different injection speeds to investigate effect of injection speed on defects formation for rheo-diecastings.Insufficient filling was observed with the speed less than 0.5m/s,however,with increasing speed to less than 2m/s,the complete shape of castings was obtained along with the cold shut formation at the end surface of casting.In addition,with injection speed higher than 7m/s,serious flash defects were generated.Microstructural observation indicates that with increasing in injection speed,the amount and size of gas-pores in microstructure are increased,while liquid segregation is decreased,and the amount and size of inclusion is increased.With the injection speed less than 1m/s,the morphology of primary solid phase is deteriorated and the secondary dendrites in liquid are increased.Therefore,although a high injection speed can increase the microstructural uniformity of casting,the increased pore and inclusion defects also generated increasingly,which is not beneficial for the improvement of mechanical properties of semisolid castings.