Heterogeneous nucleation of Pb Particles Embedded in a Zn Matrix

Zinc-10 and 20 wt pct Pb alloys have been rapidly solidified by melt spinning to obtain a very fine scale dispersion of nanometer-sized Pb particles embedded in Zn matrix. The microstructure and crystallography of the Pb particles have been studied using transmission electron microscopy (TEM). Each embedded Pb particle is a single crystal, with a truncated hexagonal biprism shape with the 6/mmm Zn matrix point group symmetry surrounded by {0001},\(\left\{ {10\bar 10} \right\}\) and\(\left\{ {10\bar 11} \right\}\) facets. The Pb particles solidify with a well-defined orientation relationship with the Zn matrix of (0001)_zn‖(111)_pb and\(11\bar 20]_{Zn} ||1\bar 10]_{Pb} \). The melting and solidification behavior of the Pb par- ticle have been studied using differential scanning calorimetry (DSC). The Pb particles solidify with an undercooling of approximately 30 K, by heterogeneous nucleation on the {0001} facets of the surrounding Zn matrix, with an apparent contact angle of 23 deg.