Effect of high pressure torsion on the precipitation hardening in Al-Ca-La based eutectic alloy

摘要

The effect of high pressure torsion (HPT) on the structure and microhardness of A13Ca2Lal·5Mn alloy containing 13 vol% of Al_4(Ca,La) eutectic phase has been studied using electron microscopy, X-ray analysis and atom probe tomography (APT). We show that HPT causes the formation of a nanocrystalline structure resulting in a 4-fold increase in the microhardness (to 2.5 GPa) of the alloy. Post-deformation low-temperature annealing further increases the microhardness to -3.1 GPa. The APT data suggest that the increase in the microhardness after annealing is caused by precipitation hardening due to the decomposition of the calcium and manganese supersaturated aluminum solid solution.