Thermal stability and deformation mechanisms in Ni-Co-Fe-Cr-Al-Ti-Nb-type nanoparticle-strengthened high-entropy alloys
Thermal stability and deformation mechanisms in Ni-Co-Fe-Cr-Al-Ti-Nb-type nanoparticle-strengthened high-entropy alloys
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DOI：
10.1016/j.jmst.2023.05.044
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
J. Hou;J.Y. Zhang;J.X. Zhang;J. Luan;Y.X. Wang;B. Cao;Y. Zhao;Z. Jiao;X.J. Liu;W. Song;P. Liaw;T. Yang
中科院分区：
文献类型：
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作者：
J. Hou;J.Y. Zhang;J.X. Zhang;J. Luan;Y.X. Wang;B. Cao;Y. Zhao;Z. Jiao;X.J. Liu;W. Song;P. Liaw;T. Yang
详细研究了L12强化Ni 39.9Co 20 Fe 15 Cr 15 Al 6 Ti 4-xNb xB 0.1（x= 0 at.%，2原子%，和4at.%）高熵合金（HEAs）。通过用Nb替代Ti，在800 °C下时效时发生球状到立方形沉淀物形态转变、粗化动力学增加和相分解。Nb的过量添加导致富Nb相的晶界析出沿着在长期时效过程中L12相分解为层状结构的D 019相。通过用Nb部分取代Ti，化学复杂且热稳定的L12相（成分为（Ni58.8Co9.8Fe2.7）（Al12.7Ti5.8Nb7.5Cr2.3））确保了稳定的相结构和清洁的晶界，从而保证了700 °C下优异的高温力学性能（屈服强度为791 ± 7 MPa，断裂强度为1013 ± 11 MPa）。观察到在塑性变形期间存在堆垛层错（SF），从而在700 °C下提供了高加工硬化能力。在800 °C时，L12合金的屈服强度出现了反常的升高，这是由于L12合金中存在具有交叉滑移组态的多层超偏位错所致。
The precipitate morphologies, coarsening kinetics, elemental partitioning behaviors, grain structures, and tensile properties were explored in detail for L12-strengthened Ni39.9Co20Fe15Cr15Al6Ti4–xNbxB0.1(x= 0 at.%, 2 at.%, and 4 at.%) high-entropy alloys (HEAs). By substituting Ti with Nb, the spheroidal-to-cuboidal precipitate morphological transition, increase in the coarsening kinetics, and phase decomposition upon aging at 800 °C occurred. The excessive addition of Nb brings about the grain boundary precipitation of an Nb-rich phase along with the phase decomposition from the L12to lamellar-structured D019phase upon the long-term aging duration. By partially substituting Ti with Nb, the chemically complex and thermally stable L12phase with a composition of (Ni58.8Co9.8Fe2.7)(Al12.7Ti5.8Nb7.5Cr2.3) ensures the stable phase structure and clean grain boundaries, which guarantees the superb high-temperature mechanical properties (791 ± 7 MPa for yielding and 1013 ± 11 MPa for failure) at 700 °C. Stacking faults (SFs) were observed to prevail during the plastic deformation, offering a high work-hardening capability at 700 °C. An anomalous rise in the yield strength at 800 °C was found, which could be ascribed to the multi-layered super-partial dislocations with a cross-slip configuration within the L12particles.