Abstract:2519A-T87 aluminum alloy was investigated in dynamic impact testing by split Hopkinson pressure bar (SHPB) and in quasistatic compression by Gleeble−1500 thermal simulation setup. The microstructures and phase compositions of compressed specimens subjected to dynamic impact testing at the strain rate range of 1 287−7 050 /s and quasistatic testing at the strain rate of 0.001 /s at room temperature were determined by TEM and XRD. The hardnesses of compressed specimens were measured by using little-duty Vickers hardness tester. The results show that the interface energy and strain energy due to external work can compensate the nucleation energy (∆G) of θ phase and lead to θ′ phase transforming into θ phase that coarsens gradually in the impacted specimen. The higher the strain rate, the lower the hardness of impacted specimens. With increasing strain rate the volume fraction of coherent or semi-coherent tetragonal θ′ phase decreases while the volume fraction of incoherent body centered tetragonal θ phase increases obviously. The most effective measure to promote the shock resistance of the alloy is to decrease the number density of θ phase evolving from θ′ phase in the impacted 2519A-T87 alloy.

Key words: 2519A aluminium alloy; microstructure; transformation; high strain rate; impact