Chromium-based bcc-superalloys strengthened by iron supplements
Chromium-based bcc-superalloys strengthened by iron supplements
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DOI：
10.1016/j.actamat.2023.119183
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发表时间：
2023-07
期刊：
影响因子：
9.4
通讯作者：
K. Ma;Thomas Blackburn;Johan P. Magnussen;Michael Kerbstadt;P. A. Ferreirós;T. Pinomaa;C. Hofer-
中科院分区：
文献类型：
--
作者：
K. Ma;Thomas Blackburn;Johan P. Magnussen;Michael Kerbstadt;P. A. Ferreirós;T. Pinomaa;C. Hofer-
铬合金正在考虑用于下一代工作温度> 800 °C的聚光太阳能应用。Cr在熔点、成本和抗氧化性方面具有优势。然而，需要改进机械性能。在此，研究了Cr（Fe）-NiAl类型的Cr基体心立方（bcc）合金，得到了包含由有序bcc NiAl金属间沉淀物（“NiAl”）强化的bcc-Cr（Fe）基体（β）的“bcc-超合金”，其中铁添加物用于定制沉淀物体积分数和高温下的机械性能。计算设计使用计算相图（CALPHAD）预测，铁增加镍和铝的溶解度，增加沉淀物的体积分数，这是实验验证。在Cr（Fe）基体中形成了晶格失配度小于0.1%的纳米级共格B2-NiAl沉淀相。Cr（Fe）-NiAl A2-B2合金表现出非常低的粗化速率（在1000 °C下为102 nm 3/h），优于铁素体基高温合金、钴基和镍基高温合金。基于粗化动力学确定了在1000/1200 °C下的低界面能为40/20 mJ/m2。低粗化速率主要归因于Ni和Al在Cr基体中的低溶解度。该合金在1000 °C下具有高达320 MPa的压缩屈服强度。Fe改性合金具有抗时效软化的能力，与低粗化速率以及作为沉淀物半径的函数的相对稳定的Orowan强化有关。添加Fe的微观结构定制提供了一种新的设计路线，以改善“Cr-超合金”的性能平衡，加速其作为一类新的高温材料的发展。
Chromium alloys are being considered for next-generation concentrated solar power applications operating > 800 °C. Cr offers advantages in melting point, cost, and oxidation resistance. However, improvements in mechanical performance are needed. Here, Cr-based body-centred-cubic (bcc) alloys of the type Cr(Fe)-NiAl are investigated, leading to ‘bcc-superalloys’ comprising a bcc-Cr(Fe) matrix (β) strengthened by ordered-bcc NiAl intermetallic precipitates (β’), with iron additions to tailor the precipitate volume fraction and mechanical properties at high temperatures. Computational design using CALculation of PHAse Diagram (CALPHAD) predicts that Fe increases the solubility of Ni and Al, increasing precipitate volume fraction, which is validated experimentally. Nano-scale, highly-coherent B2-NiAl precipitates with lattice misfit ∼ 0.1% are formed in the Cr(Fe) matrix. The Cr(Fe)-NiAl A2-B2 alloys show remarkably low coarsening rate (∼102nm3/h at 1000 °C), outperforming ferritic-superalloys, cobalt- and nickel-based superalloys. Low interfacial energies of ∼ 40/20 mJ/m2at 1000/1200 °C are determined based on the coarsening kinetics. The low coarsening rates are principally attributed to the low solubility of Ni and Al in the Cr matrix. The alloys show high compressive yield strength of ∼320 MPa at 1000 °C. The Fe-modified alloy exhibits resistance to age softening, related to the low coarsening rate as well as the relatively stable Orowan strengthening as a function of precipitate radius. Microstructure tailoring with Fe additions offers a new design route to improve the balance of properties in “Cr-superalloys”, accelerating their development as a new class of high-temperature materials.