Al-Si-Cu-Ni-Mg活塞合金中富镍相的演变

Evolution of Nickel-rich Phases in Al-Si-Cu-Ni-Mg Piston Alloys

利用XRD和热场发射(FESEM)等分析了不同含铜量Al-Si-Cu-Ni-Mg活塞合金富镍相的演变。研究结果表明:随着Cu含量的增加,镍相由Al3Ni(ε相)或Al3Cu Ni(δ相)转变为Al7Cu4Ni(γ相)其形态从短条状变为网状进而变为环形或半环形形状。此外,采用Thermo-Calc软件定量计算结果与实验结果一致。富镍相的转变对力学性能也有很大影响,在室温条件下拉伸强度由263.8 MPa降低至229.6 MPa,然后增加到278.9 MPa。然而,高温条件下抗拉强度增加了19.7%,但是合金的线性膨胀系数却持续减小。

Evolution of nickel-rich phases （Ni-phases） in A1-Si-Cu-Ni-Mg piston alloys was investigated by XRD and FESEM. The results show that, with the increase of Cu content, Ni-phasestranslatefromA13Ni（ε-phase）orAl3CuNi（δ-phase）to AlyCu4Ni （γ-phase）, and the morphologies change from short-strip shape to reticular and then annular or semi-annular shape. Moreover, the results of the quantitative calculations by Thermo-Calc software are in accordance with that of experiments. The evolutions have a great effect on mechanical properties. The tensile strength at room temperature decreases from 263.8 MPa to 229.6 MPa, and then increases to 278.9 MPa. Otherwise, the tensile strength at elevated temperature increases about 19.7%, but the coefficient of linear expansion decreases constantly.