A new class of high strength high temperature Cobalt based γ-γ′ Co-Mo-Al alloys stabilized with Ta addition
A new class of high strength high temperature Cobalt based γ-γ′ Co-Mo-Al alloys stabilized with Ta addition
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DOI：
10.1016/j.actamat.2015.06.034
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发表时间：
2015-09-15
期刊：
影响因子：
9.4
通讯作者：
Chattopadhyay, K.
中科院分区：
文献类型：
--
作者：
Makineni, S. K.;Samanta, A.;Chattopadhyay, K.
本文报道了一类新型钴基高温合金，其具有γ-γ '显微组织，并且与包括Co-Al-W基合金在内的其它市售钴基高温合金相比具有低得多的密度。基本成分为Co-10Al-5 Mo（at%），添加2at%Ta以稳定γ '相。γ-γ微观结构通过固溶和时效处理而演变。利用第一性原理计算，我们观察到Ta在稳定γ相方面起着至关重要的作用。通过在基本化学计量组成Co-3（Al，Mo）中添加Ta，与DO 19结构相比，L1（2）结构（γ ′相）的生成焓（Δ H-f）变得更负。由于Ni和Ti原子在晶格中的占据，L12结构的Al变得更负，这表明γ '沉淀物的稳定性增加。在大量的合金实验研究中，本文介绍了Co-10Al-5 Mo-2 Ta，Co-30 Ni-10Al-5 Mo-2 Ta和Co-30 Ni-10Al-5 Mo-2 Ta-2 Ti合金的详细研究结果。为了评估合金元素的作用，进行了原子探针断层扫描研究，以获得组成元素的分配系数。结果表明，Ni、Al、Ta和Ti在γ '相中有很强的配分作用。2015 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The present paper reports a new class of Co based superalloys that has gamma-gamma' microstructure and exhibits much lower density compared to other commercially available Co superalloys including Co-Al-W based alloys. The basic composition is Co-10Al-5Mo (at%) with addition of 2 at% Ta for stabilization of gamma' phase. The gamma-gamma' microstructure evolves through solutionising and aging treatment. Using first principles calculations, we observe that Ta plays a crucial role in stabilizing gamma' phase. By addition of Ta in the basic stoichiometric composition Co-3(Al, Mo), the enthalpy of formation (Delta H-f) of L1(2) structure (gamma' phase) becomes more negative in comparison to DO19 structure. The All of the L12 structure becomes further more negative by the occupancy of Ni and Ti atoms in the lattice suggesting an increase in the stability of the gamma' precipitates. Among large number of alloys studied experimentally, the paper presents results of detailed investigations on Co-10Al-5Mo-2Ta, Co-30Ni-10Al-5Mo-2Ta and Co-30Ni-10Al-5Mo-2Ta-2Ti. To evaluate the role alloying elements, atom probe tomography investigations were carried out to obtain partition coefficients for the constituent elements. The results show strong partitioning of Ni, Al, Ta and Ti in ordered gamma' precipitates. 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.