TEM characterization of melt-spun ribbons. TEM images of an Al-BNNT (3 wt.%) composite ribbon near the fractured surface after a tensile test. (a) The smallest Al grains found in the melt-spun Al-BNNT matrix; the inset depicts an EDS pattern recorded from this area. (b, c) A triple grain boundary in the Al-BNNT matrix at various magnifications; the central inset in (b) shows a representative X-ray spectrum confirming no other phases formed in the matrix except Al; the (110). (200), (220), and (311) Al peaks are marked. (c) In this case, the Al matrix is nicely oriented along the  zone axis of the fcc Al lattice. (d to f) A fading contrast peculiar to images relevant to individual multiwalled BN nanotubes present in the fractured ribbons either within the grains (d to e) or along the grain boundaries (f).
Yamaguchi et al. Nanoscale Research Letters 2013 8:3 doi:10.1186/1556-276X-8-3