열처리에 따른 알루미늄 다공성 재료의 미세구조와 기계적 특성 변화

초록

The relation between evolution of micro-structure and mechanical properties of Al-5Si-4Mg-4Cu porous material after the foaming and solution treatment were investigated. Prior to compression test with deformation rate of 0.5/s, the foam material of various densities were manufactured by powder compact foaming and heat treated at 500℃ for 120min. The ultimate compression strength at the peak stress was not changed after solution heat treatment but the flow curve above the peak one showed very smooth and uniform plateau region. This change of flow curve means that the deformation mechanism is altered from brittle fracture to ductile deformation and the energy absorption property of Al foam is dramatically improved. The improvement of energy absorption without any detriment of mechanical properties is due to that the very brittle precipitation like Al-Cu and Al-Mg was uniformly dissolved in Al matrix after solution heat treatment. Various mechanical properties of Al porous material were improved by 40% with aging of 200℃, 50min. These improvement are due to a coherent precipitates like Ω and θ″ phases.