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November 29, 2009
Access successfully TRACEs the solidification behaviour aboard a TEXUS sounding rocket mission

One step forward disclosing the solidification morphology of metals.

TRACE (Transparent Alloys for Columnar Equiaxed Solidification) is a microgravity experiment to investigate the transition from columnar to equiaxed growth (CET) in the transparent model alloy Neopentylglycol-DCamphor. The benefit of this alloy is that it solidifies like a metal and the solidification process can be observed directly by optical means.

For industrial application columnar as well as equiaxed structures are of importance. Columnar growth reduces the amount of grain boundaries, which is aspired e.g. for turbine blades or single crystals. Equiaxed growth is characterized by many small grains and causes isotropic material properties. Normally, columnar together with equiaxed microstructures in the same casting are not desired, because such a CET promotes the formation of shrinkage porosities due to bad feeding. Therefore, it is of relevance to develop a criterion predicting CET.