Al–Si alloy is widely utilized in automobile pistons and cylinders due to good castability, high strength-to-weight ratio, excellent thermal conductivity, good resistance to corrosion/oxidation, and acceptable wear resistance. To increase the efficiency of engine motor, it is imperative to modify and engineer the microstructure of Al–Si alloy to enhance the high-temperature behavior. For this reason, in the current study, different concentration of Ni (0.8% and 2%) was doped into Al–Si alloy during casting to generate various Ni-rich intermetallic compounds within the alloy matrix. AlNiCu, AlCu, AlFeSi, and Mg2Si were found to be the main intermetallic compounds precipitated within the dendritic and interdendritic regions, which could enhance the thermal stability and high-temperature performance. High-temperature compression test at high temperatures ranging from 400 to 550 °C and at different strain rates ranging from 10−3 to 1 s−1 was carried out to develop high-temperature processing map and optimize the hot workability parameters of Ni-doped Al–Si alloy. The maximum power dissipation efficiency (η) was observed within the temperature range of 450–500 °C and strain rate of 0.05–0.08 s−1 (lower strain rate) for Al–Si–0.8%Ni alloy and within the temperature range of 450–500 °C and strain rate of 0.3–1 s−1 (medium to high strain rate) for Al–Si–2%Ni alloy. Dynamic recrystallization was found to be the primary softening mechanism at high temperatures (T > 450 °C).

中文翻译：

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Ni掺杂对铸态Al-Si活塞合金组织、热变形行为和加工图的影响

由于铝硅合金具有良好的可铸性、高强度重量比、优异的导热性、良好的抗腐蚀/氧化性和可接受的耐磨性，因此广泛用于汽车活塞和气缸。为了提高发动机电机的效率，必须对 Al-Si 合金的微观结构进行改性和设计，以增强高温性能。为此，在目前的研究中，在铸造过程中将不同浓度的 Ni（0.8% 和 2%）掺杂到 Al-Si 合金中，以在合金基体中生成各种富 Ni 金属间化合物。AlNiCu、AlCu、AlFeSi 和 Mg2Si 被发现是在枝晶和枝晶区域内析出的主要金属间化合物，它们可以提高热稳定性和高温性能。进行了400～550℃高温、10-3～1s-1不同应变率下的高温压缩试验，绘制了Ni掺杂的高温加工图并优化了热加工性参数铝硅合金。对于 Al-Si-0.8%Ni 合金，在 450–500 °C 的温度范围和 0.05–0.08 s-1（较低的应变率）的应变速率下观察到最大功率耗散效率 (η)，并且在对于 Al-Si-2%Ni 合金，450–500 °C 和 0.3–1 s-1（中到高应变率）的应变速率。发现动态再结晶是高温（T > 450 °C）下的主要软化机制。