Morphology and interface structure of Mo5Si3precipitates in MoSi2

Publisher Website
Google Scholar
Abstract
Two distinctly different morphologies of Mo5Si3 precipitates have been observed in a single crystal MoSi2. Both precipitates are laths elongated along the (110) direction common to the matrix and the precipitate but differ in their cross-sectional shape and lattice orientation. Type I precipitates exhibit a rectangular cross-section, with interfaces parallel to low-index planes (110)m∥(002)p and (002)m∥(220)p, while type II precipitates are parallelograms, with their major interface at 13° to the low-index planes (002)m∥(220)p (the subscripts m and p denote the MoSi2 matrix and Mo5Si3 precipitate, respectively). The orientation relation-ships corresponding to the two characteristic morphologies differ by a 1 8° rotation around the lath axis. A periodic array of dislocation loops and associated ledges enveloping the precipitates were revealed by high-resolution electron microscopy and selected area electron diffraction. The Burgers vector of these dislocations was determined unambiguously from high-resolution images in orthogonal viewing directions. The differences between the two characteristic morphologies and their orientation relationships are due to a difference in the stacking sequence of ledges.

This publication has 9 references indexed in Scilit: