Competitive relationship between thermal effect and grain boundary precipitates on the ductility of an as-quenched Al–Cu–Mn alloy

The ductility of an Al–Cu–Mn alloy is typically characterized by fracture strain and is influenced by experimental temperature and its microstructure. Previous researches show that the ductility increases with the temperature and decreases with the strain rate. However, based on the results of isothermal tensile tests of as-quenched Al–Cu–Mn alloy in this paper, it was found that the ductility decreased apparently (approximately 90% under strain rate of 0.001/s) at a medium temperature range (573–673 K) and gradually reincreased to its original level at higher temperature. A competitive relationship between temperature softening and grain boundary T precipitation was proposed to account for the unusual variation of ductility. In addition, a ductility model based on the competitive relationship was deduced to quantify the evolution of the fracture strain for the as-quenched Al–Cu–Mn alloy and validated by the experimental results.