Research of quasi-solid fracture behavior of casting AI-4.5Cu alloys

1. Introduction Casting Al-Cu alloy with high strength is widely used for its excellent properties in common temperature and high temperature applications. However, this family of alloys has a very special solidification behavior, i.e. wider solidification range, which will result in an inferior cast- ing performance and severe tendency to hot cracking. Hot crack[1] is a very dangerous solidification defect in casting and welding processes. But, up to day, the research on hot cracking is stil…

Research of quasi-solid fracture behavior of casting AI-4.5Cu alloys

The influencing mechanisms of elements Ti and Ce and their interactions on fracture behaviors of casting alloys AI-4.5Cu-0.6Mn were studied by observing tensile fracture behavior in quasi-solid zone under SEM and EDX instruments. The results indicate that the resistance stress against hot cracking can be improved obviously by addition of Ti, because of its grain refining function. It is also found that, when Ce is added into the alloys, besides its effect in refining crystalline, the mechanical behavior of lower melting point eutectic phase in quasi-solid zone can be improved efficiently by some compounds with Ce formed and deposited between dendrites. Therefore, a colligating effect of Ti and Ce on improving resistance stress against hot cracking is more efficient than that only single alloy element is applied. When hot cracking occurs, grains yield at first, and then crack spreads. Both inter-grain and trans-grain fractures are observed, but the major fracture manner is brittleness.