Influence of minor additions on Icosahedral Short-Range Order (ISRO) and its consequences on nucleation and solidification growth kinetics in fcc alloys

Joint 5th International Conference on Advances in Solidification Processes;5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining

土木建筑工程;计算机科学

Zollinger, J.^1 ; Rappaz, M.^2

Institut Jean Lamour, Department of Metallurgy and Materials Science and Engineering, Université de Lorraine, Campus ARTEM, Allée André Guinier, Nancy

F-54011, France^1

Institute of Materials, École Polytechnique Fédérale de Lausanne, Lausanne

CH-1015, Switzerland^2

关键词: Crystallographic analysis;    Growth directions;    Icosahedral quasicrystals;    Icosahedral short-range orders;    Kinetics effects;    Nucleation mechanism;    Recent progress;    Solute elements;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/529/1/012045/pdf
DOI  :  10.1088/1757-899X/529/1/012045

来源: IOP

【 摘 要 】

The present contribution reviews the recent progress related to the influence of Icosahedral Short-Range Order (ISRO) and icosahedral Quasicrystals (i-QC) formation on the solidification of fcc alloys through minor solute element additions. From intensive crystallographic analysis of multi-twinned regions in as-cast Al-based and Au-based fcc alloys, Kurtuldu et al. have shown recently that a so-called "iQC-mediated" nucleation mechanism occurs when a few hundred ppm of Cr and Ir, respectively, are added to the melt [1] [2]. Similarly, it appears that the growth directions of dendrites in Al-Zn:Cr is also influenced by ISRO in the liquid, thus showing an attachment kinetics effect [3]. In a recent contribution, we have shown that iQC-mediated nucleation also occurs in pink gold alloys with Ir-additions, but two additional phenomena at high solidification speed [4]: (i) a spinodal-type decomposition of the liquid, leading to the formation of twinned Cu precipitates in addition to multi-twinned Au-rich grains; (ii) a change of the microstructure of the Au-rich grains, from 〈100〉 dendrites to 〈111〉 textured cells in the columnar zone.