Differential role of nanoscaled oxide dispersoids (Y2O3vs Al2O3) in the high-temperature structural stability of NiCr alloys
Differential role of nanoscaled oxide dispersoids (Y2O3vs Al2O3) in the high-temperature structural stability of NiCr alloys
复制标题
DOI：
10.1007/s11661-006-1041-7
复制
发表时间：
2006-12
期刊：
影响因子：
--
通讯作者：
D. Srinivasan;P. R. Subramanian
中科院分区：
文献类型：
--
作者：
D. Srinivasan;P. R. Subramanian
研究了纳米弥散体对纳米晶镍铬合金高温稳定性的影响。与氧化铝颗粒相比，纳米级氧化钇弥散体在保持 NiCr 合金中细粒微观结构（通过电子束物理气相沉积 (EB-PVD) 途径）方面要有效得多。细小的氧化钇颗粒（<20 nm）与基体具有共同的取向关系，并发挥齐纳钉扎力来抑制高温下晶粒的快速生长。氧化钇的粗化是通过金属物质通过 NiCr 基体的扩散而发生的，与氧化铝颗粒相比是微乎其微的，而氧化铝颗粒由于粗化而经历了一系列相变（γ（尖晶石）→δ→α）。纳米级的相选择已根据相应尺寸范围内亚稳态与稳态相形成的自由能进行了研究。造成两种类型弥散体之间粗化作用不同的主要因素归因于它们在这些高温下的相对形成自由能。
The effect of nanoscaled dispersoids in contributing to the high-temperature stability of nanograined NiCr alloys has been studied. Nanoscale yttria dispersoids were far more effective in contributing to the retention of a fine-grained microstructure in NiCr alloys (viathe electron beam-physical vapor deposition (EB-PVD) route) as compared to the alumina particles. The fine yttria particles (<20 nm) shared a common orientation relationship with the matrix and exerted a Zener pinning force to inhibit rapid grain growth at elevated temperatures. Coarsening of yttria took place by diffusion of the metallic species through the NiCr matrix and was marginal compared to the alumina particles, which underwent a hierarchy of phase transformations (γ(spinel)→δ→α) as an outcome of coarsening. Phase selection at the nanoscale has been examined on the basis of free energies of formation of the metastablevsstable phases at the respective size ranges. The main factor responsible for the differential role of coarsening between the two types of dispersoids has been attributed to their relative free energies of formation, at these elevated temperatures.