سجاد رسائی

Al–Si alloy is widely utilized in automobile pistons and cylinders due to goodcastability, high strength-to-weight ratio, excellent thermal conductivity, goodresistance to corrosion/oxidation, and acceptable wear resistance. To increasethe efficiency of engine motor, it is imperative to modify and engineer themicrostructure of Al–Si alloy to enhance the high-temperature behavior. For thisreason, in the current study, different concentration of Ni (0.8% and 2%) wasdoped into Al–Si alloy during casting to generate various Ni-rich intermetalliccompounds within the alloy matrix. AlNiCu, AlCu, AlFeSi, and Mg2Si werefound to be the main intermetallic compounds precipitated within the dendriticand interdendritic regions, which could enhance the thermal stability and high-temperature performance. High-temperature compression test at high temper-atures ranging from 400 to 550°C and at different strain rates ranging from 10-3to 1 s-1was carried out to develop high-temperature processing map andoptimize the hot workability parameters of Ni-doped Al–Si alloy. The maximumpower dissipation efficiency (g) was observed within the temperature range of450–500°C and strain rate of 0.05–0.08 s-1(lower strain rate) for Al–Si–0.8%Nialloy and within the temperature range of 450–500°C and strain rate of0.3–1 s-1(medium to high strain rate) for Al–Si–2%Ni alloy. Dynamic recrys-tallization was found to be the primary softening mechanism at high tempera-tures (T[450°C).