Effect of convection on the dendrite growth kinetics in undercooled melts of D2 tool steels

4th International Conference on Advances in Solidification Processes

材料科学;物理学

Valloton, J.^1,2 ; Herlach, D.M.^2 ; Henein, H.^1

Advanced Materials and Processing Laboratory, University of Alberta, Edmonton, Canada^1

Institut für Materialphysik im Weltraum, DLR, Cologne

51170, Germany^2

关键词: Dendrite growth;    Dendritic microstructure;    Electromagnetic levitation;    Equiaxed structures;    Eutectic carbide;    Parabolic flight experiments;    Reduced gravity;    Undercooled melt;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/117/1/012058/pdf
DOI  :  10.1088/1757-899X/117/1/012058

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Rapid solidification of D2 tool steel is investigated experimentally using the electromagnetic levitation technique under terrestrial and reduced gravity conditions. The microstructures of samples covering a broad range of undercoolings (40 K ≤ ΔT ≤ 280 K) are analysed. At low undercooling coarse grained dendritic microstructure is observed, while at higher undercoolings this dendritic feature disappears in favour of a grain refined equiaxed structure. In the latter case, the eutectic carbides are more evenly dispersed throughout the microstructure. The sample solidified in microgravity during parabolic flight experiment exhibits only a few very large grains with twinning relationship. This highlights the effect of convection on grain refinement in this system.