On the microtwinning mechanism in a single crystal superalloy
On the microtwinning mechanism in a single crystal superalloy
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DOI：
10.1016/j.actamat.2017.05.072
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发表时间：
2017-08-15
期刊：
影响因子：
9.4
通讯作者：
Reed, R. C.
中科院分区：
文献类型：
--
作者：
Barba, D.;Alabort, E.;Reed, R. C.
研究了微孪晶机制对单晶高温合金MD2蠕变行为的贡献。当应力范围为625~675 Mpa时，沿(011)方向的应力范围为800℃时，微孪晶较为普遍；当应力范围为625 Mpa时，沿(011)方向加载时，则普遍存在微孪晶。利用定量体视学方法，估算了孪晶比例和孪晶厚度；这允许恢复累积的蠕变应变，进而支持微孪晶模式在赋予变形中的作用。原子探针断层扫描证实了铬和钴在孪晶/母相界面的偏析，这与支持孪晶加长和增厚所需的层错能的降低是一致的。提出了孪晶的扩散控制生长模型，并用该模型恢复了测量的蠕变应变率。这项工作为建立符合微孪生机制的变形热力本构模型奠定了基础。(C)2017 Acta Materialia Inc.，由Elsevier Ltd.出版。
The contribution of a microtwinning mechanism to the creep deformation behaviour of single crystal superalloy MD2 is studied. Microtwinning is prevalent for uniaxial loading along (011) at 800 degrees C for the stress range 625 to 675 MPa and 825 degrees C for 625 MPa. Using quantitative stereology, the twin fraction and twin thickness are estimated; this allows the accumulated creep strain to be recovered, in turn supporting the role of the microtwinning mode in conferring deformation. Atom probe tomography confirms the segregation of Cr and Co at the twin/parent interface, consistent with the lowering of the stacking fault energy needed to support twin lengthening and thickening. A model for diffusion controlled growth of twins is proposed and it is used to recover the measured creep strain rate. The work provides the basis for a thermo-mechanical constitutive model of deformation consistent with the microtwinning mechanism. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd.