Thermal Mechanical Processing of Press and Sinter Al-Cu-Mg-Sn-(AlN) Metal Matrix Composite Materials

The forging of sintered aluminum powder metallurgy alloys is currently viewed as a promising industrial technology for the manufacture of complex engineered products. The powder metallurgy process facilitates the use of admixed ceramic particles to produce aluminum metal matrix composites. However, fundamental data on the thermal-mechanical response of commercially relevant powder metallurgy alloy systems under varying conditions of temperature and strain rate are lacking. To address this constraint, the current study investigates the thermal-mechanical processing response of a family of metal matrix composite materials that employ a commercially exploited base alloy system coupled with admixed additions of aluminum nitride. Industrially-sintered compacts were tested under hot compression using a Gleeble 3500 thermal-mechanical test system to quantify their flow behavior. The nominal workability was assessed as a function of material formulation, sintered preform condition, and processing parameters (temperature and strain rate). Optical metallography and electron backscatter diffraction were used to observe the grain evolution through deformation. Full densification was achieved for materials with ceramic concentrations of 2% volume or less. Zener-Hollomon constituent analyses were also completed to elucidate a more comprehensive understanding the flow behavior inherent to each material. Flow behavior varied directly with the sintered density, which was influenced by the concentration and nature of ceramic particulate.