Generation and Progress Behavior of Strain-Induced Abnormally Large Grains in Superalloy 718
Generation and Progress Behavior of Strain-Induced Abnormally Large Grains in Superalloy 718
复制标题
718高温合金中应变引起的异常大晶粒的产生和进展行为
DOI：
10.1007/s11661-020-05838-6
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Oikawa Katsunari
中科院分区：
文献类型：
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作者：
Aoki Chuya;Date Masayoshi;Ueno Tomonori;Ohno Takehiro;Oikawa Katsunari
在本文中，使用压缩测试和低于980 °C的δ相固溶线温度的后续热处理来研究与高温合金718中的应变诱导的异常大晶粒相关的行为。异常大晶粒的核包括一些通过成核新再结晶的晶粒。异常大的晶粒是由动态再结晶晶粒和变形基体之间的晶内取向差的差异造成的。异常大的晶粒的起始被延迟响应于塑性应变的减少，导致形成由具有更复杂形态的较大晶粒组成的微观结构。晶界迁移的方向垂直于，或主要是在一个方向上平行于，的α 3 {111}孪晶界，沿着与高阶孪晶的形成。为了确定平行于α 3 {111}孪晶晶界的方向，使用{110} PF分析了母晶粒和异种孪晶沿沿着其孪晶晶界在相同方向上生长的区域。生长方向仅由一组公共轴组成<110>，使得原子的排列是一致的。由于多重孪生，异常大的晶粒似乎在不同的生长方向上进化。
Herein, the behavior associated with strain-induced abnormally large grains in superalloy 718 was investigated using compression testing and subsequent heat treatment below theδ-phase solvus temperature of 980 °C. The nuclei of abnormally large grains included some grains that were newly recrystallized through nucleation. Abnormally large grains were caused by a difference in intragranular misorientation between the dynamic recrystallized grains and the deformed matrix. The initiation of abnormally large grains was retarded in response to a decrease in plastic strain, leading to the formation of microstructures consisting of larger grains with a more complex morphology. Grain boundaries migrated locally in a direction perpendicular to, or predominantly in a direction parallel to, the Σ3 {111} twin boundaries, along with the high-order twin formation. To determine the direction parallel to the Σ3 {111} twin boundaries, the regions where parent grain and dissimilar twin growth occurred in the same direction along their twin boundaries were analyzed using {110} PFs. The growth direction consisted of only one set of common <110> axes such that the arrangement of atoms was consistent. Owing to multiple twinning, abnormally large grains seemed to evolve in varying growth directions.