ABSTRACT
Aluminum A356 alloys have several interesting properties to be used in automobile
and aircraft industries. Recent studies have shown that the properties of cast
aluminum alloys are modified by the insertion of reinforcement nanoparticles. This
study investigates the microstructure and mechanical properties of ZrO2
nanoreinforced A356 alloy in T6 heat treated condition. Some samples of as cast
monolithic A356 and 3% ZrO2 nanoparticles (30nm) reinforced A356 were
prepared by stir casting from the semi-solid state followed by T6 heat treatment
process. The samples were solution treated at temperature of 550°C for 2hours
followed by aging at different temperatures (170°C&180°C), for different aging time
(2hr,4hr&6hr). The results obtained in this work showed enhancement in the
mechanical properties (ultimate strength, ductility and hardness). The as cast
samples showed values of 119 MPa,4.5% &23 HRB, respectively, while the
3%ZrO2 reinforced samples showed the values of 165MPa,4.7% &60 HRB,
respectively. After T6 heat treatment, the same values changed to 198MPa, 6.4%
&70HRB, respectively for the nanoreinforced samples. The microstructure
morphology was changed from lamellar eutectic structure to spheriodized eutectic
structure.