Direct observation of dendrite fragmentation in the solidification of undercooled melts

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

Mullis, Andrew M.^1 ; Haque, Nafisul^1

School of Chemical and Process Engineering, University of Leeds, Leeds, United Kingdom^1

关键词: Dendrite fragmentations;    Direct observations;    Fragmentation process;    Rapidly solidified structures;    Single phase;    Solidification microstructures;    Solidified materials;    Undercooled melt;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/529/1/012020/pdf
DOI  :  10.1088/1757-899X/529/1/012020

来源: IOP

【 摘 要 】

The fragmentation of dendrites immediately following the recalescence phase of growth during the solidification of undercooled melts has been invoked to explain various rapid solidification microstructures. Despite this, little direct evidence of such a fragmentation process usually survives in the as-solidified material. We report on the rapid solidification of the single phase, congruently melting intermetallic β-Ni3Ge. During equilibrium solidification this material solidifies to the chemically ordered L12 crystal structure. Conversely, during rapid solidification, disorder trapping results in solidification to a random fcc solid solution, thereby providing a means to distinguish the rapidly solidified structures. We present results which show a range of microstructures in which the dendrite fragmentation process has been captured in progress. Results from EBSD Euler mapping reveal that dendrite fragmentation is a potential, but not particularly efficient, route to grain refinement.