材料科学
奥氏体
合金
热力学
工作(物理)
密度泛函理论
原子探针
临界半径
体积分数
降水
微观结构
相(物质)
联轴节(管道)
冶金
计算化学
复合材料
化学
几何学
物理
气象学
有机化学
数学
曲率
作者
Ying Yang,German D. Samolyuk,Tianyi Chen,Jonathan D. Poplawsky,Andrew R. Lupini,Lizhen Tan,Kenneth C. Littrell
标识
DOI:10.1016/j.matdes.2020.108592
摘要
Achieving a high-volume fraction of thermodynamically stable L12-type precipitates that are resistant to coarsening is of great importance for the development of low-cost FeNi based austenitic steels. With the aid of computational thermodynamics, this work designed two model alloys: Fe-37.4Ni-6.1Al-2.9Ti (FNAT) and Fe-45.2Ni-5.9Al-8.5Si (FNAS). Both alloys were designed to contain a similar amount of L12 precipitate in Fe-Ni matrix without forming other precipitates. Density-Function-Theory (DFT) calculation was coupled with computational thermodynamics to predict the critical radius at which the precipitates change shape from spherical to cuboidal. The calculation results suggest that critical radius for the FNAT alloy is about two orders of magnitude larger than that for the FeNiAlSi alloy. Phase stability and morphology of the L12 precipitates in these two alloys were experimentally investigated through X-ray diffraction, atom probe tomography, and scanning and transmission electron microscopy. The L12 precipitates in the FeNiAlSi system were found to be cuboidal and rod shaped, with much larger size than the spherical ones in the FeNiAlTi system, agreeing with the calculation results. This work suggested that coupling computational thermodynamics with DFT calculations can be reliably used to design L12 precipitates in FeNi based alloys.
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