Effects of Cr on the properties of multicomponent cobalt-based superalloys with ultra high γ’ volume fraction
Effects of Cr on the properties of multicomponent cobalt-based superalloys with ultra high γ’ volume fraction
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DOI：
10.1016/j.jallcom.2020.154790
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发表时间：
2020-08
影响因子：
6.2
通讯作者：
D. Chung;J. P. Toinin;E. Lass;D. Seidman;D. Dunand
中科院分区：
文献类型：
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作者：
D. Chung;J. P. Toinin;E. Lass;D. Seidman;D. Dunand
已知铬赋予钴基超合金抗氧化性。本文研究了Cr含量对Co-30 Ni-11 Al-2 Ti-5.5 W-2.5 Ta-0.1 B（at.%）合金性能的影响，具有高“体积分数（高达98%）。添加4、8或12 at.% Cr降低了γ ′-固溶线温度和γ ′-体积分数，同时也降低了γ ′-颗粒的平均半径。同步辐射X射线衍射和原子探针层析证实，Cr通过改变W在γ-和γ '-相之间的分配行为来减小晶格参数失配。同时，Cr含量的增加显著提高了合金的抗氧化性。结果表明，4at.% Cr足以将氧化速率降低两个数量级。在850 ℃下的蠕变研究表明，Cr不会对高γ '体积分数Co基高温合金的蠕变性能产生不利影响，但γ'筏化趋势随Cr浓度而变化。与Ni 3Al金属间化合物相比，高α ′体积分数的合金具有更高的抗蠕变性能.这可归因于由添加Cr、Ti或Ta引起的反相边界能的增加，以及Co基金属间化合物中显著的固溶硬化。
Chromium is known to confer oxidation resistance on Co-based superalloys. Herein we studied the influence of Cr concentration on the properties of a Co-based superalloy, Co–30Ni–11Al–2Ti-5.5 W-2.5 Ta-0.1 B (at.%), with high γ’-volume fractions (up to 98%). Additions of 4, 8, or 12 at.% Cr decreased the γ’-solvus temperature and the γ’-volume fraction, while also reducing the mean radius of γ’-particles. Synchrotron X-ray diffraction and atom-probe tomography confirmed that Cr reduces the lattice parameter misfit by altering the partitioning behavior of W between the γ-and γ’-phases. Concomitantly, an increase in Cr content significantly improved the oxidation resistance of the alloy. The results indicate that 4 at.% Cr is sufficient to decrease the oxidation rate by two orders of magnitude. A creep study at 850∘ C revealed that Cr does not affect adversely the creep performance in high γ’-volume fraction Co-based superalloys, but the tendency toward γ’rafting changes with Cr concentration. Compared to Ni 3 Al intermetallic compounds, the alloys with high γ’-volume fraction studied exhibited a significantly higher creep resistance. This may be attributed to the increase in antiphase boundary energy caused by the addition of Cr, Ti, or Ta, and significant solid-solution hardening in the Co-based intermetallic γ’-phase.