Hot deformation behaviors and hot processing maps of AlSi37Cu0.7Mg0.9Ni0.2 aluminum alloy prepared by rapid solidification and hot pressure

To study the high-temperature rheological behavior and hot working process window of AlSi37Cu0.7Mg0.9Ni0.2 alloy, isothermal hot compression experiments were conducted on the alloy using Gleeble-3500 thermal simulation testing machine under deformation temperatures of 280-530 °C and strain rates of 0.01-25 s -1 . True stress-true strain curves were obtained at different strain rates and temperatures, and the hot processing maps of the alloy were constructed based on the DMM principle. The microstructure and fracture surfaces of the alloy under different hot deformation conditions were observed. The results indicated that the flow stress of the alloy was influenced by the deformation temperature and strain rate significantly, that is, it decreased with the rise of deformation temperature and increased with the rise of strain rate. The activation energy of hot compression deformation was 188.679 kJ·mol -1 . The hot processing maps constructed predicted the hot working performance of the alloy accurately, and the optimum hot processing domain was determined to be at temperature of 480-510 °C and strain rate of 0.01-1 s -1 . The specimens were likely to become unstable and cracks occurred along the interface at temperature above 500 °C and strain rate above 1 s -1 . The dissociation fractures occurred mainly at the interface between the α-Al matrix and heterogeneous particles.