  The solidification behavior of a eutectic AlCu specimen is investigated via
in situ scanning transmission electron microscope (STEM) experiments.
Solidification conditions are varied by imposing various cooling rates via a
micro-electro-mechanical system (MEMS) based membrane. The methodology allows
the use of material processed by a melting and casting route close to
industrial metallurgically fabricated material for in situ STEM solidification
studies. Several rapid solidification morphologies could be obtained solely on
a single specimen by the demonstrated strategy. A change from nanometer scaled
lamellar to dendritic morphology is observed by differing cooling from medium
to the highest tested rates. Cooling rates of 100, 10000 and 30000 K/s are
used. For the comparatively slow cooling rate of 100 K/s, a coarser
three-dimensional morphology is gained. Additional post-solidification heat
treatments are investigated in terms of observation of spheroidization of
lamellas during annealing at elevated temperatures.
