Effect of Nb Alloying Addition on Local Phase Transformation at Microtwin Boundaries in Nickel Based Superalloys
Effect of Nb Alloying Addition on Local Phase Transformation at Microtwin Boundaries in Nickel Based Superalloys
复制标题
Nb 合金添加对镍基高温合金微孪晶界局部相变的影响
DOI：
10.1007/978-3-030-51834-9
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
A.J. Egan, Y. Rao
中科院分区：
文献类型：
--
作者：
A.J. Egan, Y. Rao
这项工作研究了两个名义上相似的多晶合金，Nb含量的细微差别，旨在阐明其在高温蠕变过程中的局部相变强化的效果。在750 °C和600 MPa下进行测试，以针对由超晶格本征和非本征堆垛层错以及微孪晶主导的蠕变状态。发现具有较高Nb和较低Al的合金A在蠕变强度方面上级具有较低Nb和较高Al的合金B以及先前研究的ME3和LSHR。原子分辨率扫描透射电子显微镜和能量分散光谱发现，这种蠕变强度的增加是由于Nb增加导致沿着微孪晶边界界面发生的新型局部相变。互补密度泛函理论计算有助于确认这是χ相形成。据推测，这种转变是合金A表现出的蠕变强度增加的原因。
This work investigates two nominally similar polycrystalline alloys, with a subtle difference in Nb content, intended to elucidate its effect on local phase transformation strengthening during high temperature creep. Tests were conducted at 750 °C and 600 MPa to target the creep regime dominated by superlattice intrinsic and extrinsic stacking faults, as well as microtwinning. Alloy A, with higher Nb and lower Al, was found to be superior in creep strength to Alloy B, with lower Nb and higher Al, as well as previously investigated ME3 and LSHR. Atomic resolution scanning transmission electron microscopy and energy-dispersive spectroscopy found that this increased creep strength was due to a novel local phase transformation occurring along microtwin boundary interfaces as a result of the Nb increase. Complementary density functional theory calculations helped to confirm that this was χ phase formation. It is hypothesized that this transformation was the cause of the increased creep strength exhibited by Alloy A.