Different content Al-Ti-C refiner was added into 2219 aluminum alloy

during the solidification and the microstructure of ingots with different Al-Ti-C refiner was analyzed comparatively by OM and DSC.The effects of Al-Ti-C refiner on nucleation and undercooling degree of 2219 aluminum alloy during the solidification were investigated.The results reveal that the microstructure is refined with Al-TiC refiner and the satisfied refinement effects can be observed with 0.5%refiner.The unercooling degree of the aluminum melt is affected by refiner content

where it is decreased gradually with the increase of refiner content

however

with refiner content more than 0.5%

decrease of undercooling degree can be ignored.TiC particles from decomposition of Al-Ti-C refiner can be acted as the nuclei of heterogeneous nucleation

and these particles will gather to increase the substrate size

which decreases the contact angle and the critical nucleation energy

finally the undercooling degree needed for nucleation is decreased.