Piston aluminum alloys have different intermetallic phases, such as Cu3Al, Mg2Si and AlNi phases.
morphology and the distribution of such phases have important roles on mechanical
properties of the piston material.
Therefore, in this research, various ageing heat treatments were
done on the mentioned material and the microstructural
feature and the hardness were studied.
Obtained results showed that solutioning at 515 °C for 7 hrs and ageing at
205 °C for 7 hrs,
was the superior heat treatment process, since such treatment led to increase the hardness value
its highest value (153 BHN) for the piston aluminum alloy. This heat treatment caused to increase
the size of Si
particles obviously and caused to precipitate other intermetallic phases of Al
(Ni,Cu) and Ni-Si. Additionally,
solutioning at 500 °C for 5 hrs and ageing at 180 °C for 9
hrs resulted in coarsening Si and Al-Ni participates
in the longitudinal direction, which was caused
to increase the hardness value to 137 BHN. EDS results indicated that
when the specimen aged at 230
°C for 5 hrs, other intermetallic phases such as Al (Ni,Si) and Mg2Si were appeared in