Fragility and structure of Al–Cu alloy melts

The dynamic viscosity measurements are performed for Al–Cu alloy melts with different compositions using an oscillating-cup viscometer. The results show that the viscosities of Al–Cu alloy melts increase with the copper content increasing, and also have a correlation with the correlation radius of clusters, which is measured by the high-temperature X-ray diffractometer. It has also been found that the fragilities of superheated melts (M) of hypereutectic Al–Cu alloys increase with the copper content increasing. There exists a relationship between the fragility and the structure in Al–Cu alloy melts. The value of the M reflects the variation of activation energy for viscous flow.