Abstract This study investigated the precipitation behavior of nanoscale Cu and Ni3Al particles in multi-component ultra-high strength steel (UHSS) and its influence on mechanical properties. The precipitation nanostructural features and matrix microstructural features of UHSS were carefully characterized by HRTEM, XRD and EBSD. Addition of Cu and Al in Fe-Ni steel increased the dislocation density of martensite and promoted the co-precipitation of Cu and Ni3Al nanoparticles upon aging. The Fe-Ni-Cu-Al steel achieved a yield strength of 1350 MPa at 525 °C aging for 2 h, of which ~950 MPa is contributed by dislocation strengthening and co-precipitation strengthening. The dislocation density in experimental steels was determined in the range of 1015 m−2, which gave rise to a strengthening contribution of over 400 MPa. Meanwhile, the extremely high dislocation density acted as preferred precipitation sites for the co-precipitation of nanoscale Cu and Ni3Al particles. The contribution of co-precipitation strengthening was calculated as 413 MPa, while the contribution of strengthening relying on solely Cu precipitation in Fe-Ni-Cu steel was only 144 MPa. As increasing the aging temperature, Ni3Al particles showed faster coarsening rate than that of Cu particles, which led to a significant decrease in the strengthening increment of Fe-Ni-Cu-Al steel.

中文翻译：

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多组分超高强钢力学性能及纳米颗粒析出行为

摘要 本研究研究了纳米级Cu 和Ni3Al 颗粒在多组分超高强度钢(UHSS) 中的析出行为及其对力学性能的影响。UHSS 的沉淀纳米结构特征和基体微观结构特征通过 HRTEM、XRD 和 EBSD 进行了仔细表征。Fe-Ni钢中Cu和Al的加入增加了马氏体的位错密度，促进了时效过程中Cu和Ni3Al纳米颗粒的共沉淀。Fe-Ni-Cu-Al 钢在 525 °C 时效 2 h 时达到 1350 MPa 的屈服强度，其中~950 MPa 由位错强化和共沉淀强化贡献。实验钢中的位错密度确定在 1015 m-2 的范围内，这产生了超过 400 MPa 的强化贡献。同时，极高的位错密度是纳米级 Cu 和 Ni3Al 颗粒共沉淀的首选沉淀位点。共沉淀强化的贡献计算为413 MPa，而Fe-Ni-Cu钢中仅依靠Cu沉淀强化的贡献仅为144 MPa。随着时效温度的升高，Ni3Al 颗粒的粗化速度比 Cu 颗粒的粗化速度快，导致 Fe-Ni-Cu-Al 钢的强化增量显着降低。