Presence of ε and ε crystal structures in rapidly solidified intermetallic compound Ni5Ge3

[摘要] The congruently melting, single phase intermetallic Ni5Ge3 has been subject to rapid solidification via droptube processing wherein powders, with diameters between > 850 and 150 mu m, are produced. At low cooling rates (> 850 mu m diameter particles, < 700 K s(-1)) the dominant solidification morphology, revealed after etching, is that of partial plate and lath microstructure in an otherwise featureless matrix. At slightly high cooling rates (850-150 mu m diameter particles, 700-7800 K s(-1)) complete plate & lath microstructure ob-served, again imbedded within a featureless matrix. Selected area diffraction analysis in the TEM reveals that partial plate & lath are the disordered form of.-Ni5Ge3 in a matrix of the ordered (double-superlattice) form. Partial plate & lath has a very different EBSD to the plate & lath structure. Histogram of the correlated grain orientation angle distribution across grain orientation in partial plate & lath microstructure sample from the > 850 mu m fraction showing random grain orientation. However, grain orientation in plate & lath structure from 300 to 212 mu m fraction displaying the distribution predominance of low angle grain boundaries. (C) 2021 Elsevier B.V. All rights reserved.

[发布日期] 2021-12-20

[关键词] Rapid solidification;Intermetallic compound;Plate & lath microstructure