Effect of gradient microstructure on elevated temperature mechanical properties of Ni-based superalloy ATI 718Plus
Effect of gradient microstructure on elevated temperature mechanical properties of Ni-based superalloy ATI 718Plus
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DOI：
10.1016/j.msea.2022.143124
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发表时间：
2022-04
期刊：
影响因子：
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通讯作者：
Yayun Li;Pingwei Xu;Wei Jiang;Lei Zhou;Zihao Jiang;Yi-long Liang;Yu Liang
中科院分区：
文献类型：
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作者：
Yayun Li;Pingwei Xu;Wei Jiang;Lei Zhou;Zihao Jiang;Yi-long Liang;Yu Liang
研究了超声表面滚压工艺及后处理对ATI 718 Plus组织和高温拉伸性能的影响。热处理后，在USRP处理的样品表面产生了η-Ni 3（Al0.5Nb0.5）相和再结晶晶粒的梯度分布。梯度层中η相的数量随深度的增加而减少，而晶粒尺寸则表现出相反的趋势。在704 °C的高温下，这些η相颗粒分布在梯度组织的晶界上，细化了晶粒，稳定了跨尺度的晶粒等级。这种非均匀的微观结构促进了塑性变形过程中在GB和η相附近高密度几何必需位错（GND）的积累，从而导致额外的硬化。在拉伸试验中，非均匀组织中的中心粗晶组织经受最大的塑性变形，并保持塑性。在704 °C的拉伸试验中，与标准试样相比，超声轧制试样的屈服强度（YS）和极限拉伸强度（UTS）提高了约12%，而没有明显的塑性劣化发生。该研究有助于提高对高温合金中平衡第二相作用机理以及平衡相分布状态对力学性能影响的认识。
The effect of the ultrasonic surface rolling process (USRP) and post-treatment on the microstructure and elevated-temperature tensile properties of ATI 718Plus were investigated. The gradient distribution of the η-Ni3(Al0.5Nb0.5) phase and recrystallized grains was generated on the surface of the USRP-treated samples after heat treatment. The amount of η phase in the gradient layer decreased with increasing depth, whereas grain size showed the opposite trend. These η phase particles, distributed in the grain boundaries (GBs) of the gradient microstructure with refined grains, stabilized thetrans-scale grain hierarchy at a high temperature of 704 °C. This heterogeneous microstructure promotes the accumulation of high-density geometrically necessary dislocations (GNDs) near the GBs and η phase during plastic deformation, resulting in additional hardening. The central coarse grains in the heterogeneous structure were subjected to the most plastic deformation and conserved ductility during the tensile tests. Compared with the standard sample, the yield strength (YS) and ultimate tensile strength (UTS) of the ultrasonically rolled samples increased by approximately 12% during tensile tests at 704 °C, without distinct plastic deterioration occurring. This study helps to improve the understanding of the functional mechanism of the equilibrium secondary phase in superalloys and the influence of the distribution state of the equilibrium phase on the mechanical properties.