Effects of temperature and holding time on the semi-solid isothermal heat-treated microstructure of ZL104 aluminum alloy

The feasibility of fabricating ZL104 aluminum alloy with non-dendritic microstructure by a semi-solid isothermal heat treatment process and the effects of temperature and holding time on the semi-solid isothermal heat-treated microstructure of the alloy were investigated.The results indicate that it is possible to produce ZL104 alloy with non-dendritic microstructure by suitable semi-solid isothermal heat treatment.With the holding time increasing from 30 to 120 min for a given holding temperature of 580 ℃,or the holding temperature increasing from 570 to 580 ℃ for a given holding time of 120 min,the average size and globular trendance of unmelted primary solid particles in the semi-solid alloy decrease and become more obvious,respectively.Under the experimental condition of this paper,the optimal semi-solid isothermal heat treatment processing,580 ℃ for 120 min,is obtained for the alloy.Under the optimal process,the ZL104 alloy can obtain a non-dendritic microstructure with a 49% liquid content and a average size range of 115 μm of the unmelted primary solid particles,which could meet the need of the following semi-solid forming.