HYDROGEN POROSITY IN DIRECTIONAL SOLIDIFIED ALUMINUM-COPPER ALLOYS - IN-SITU OBSERVATION

Using a temperature gradient stage and real time micro-focus radiograp hy the formation of porosity was observed in situ during the solidific ation of aluminium-copper alloys. Pore morphology was characterized bo th in the final structure and as a function of temperature during soli dification, providing a qualitative insight into the relative importan ce of the competing physical processes. The effect of solidification v elocity, thermal gradient and alloy composition on both the growth kin etics and final structure of the porosity was quantified. Statistical analysis was used to compare the trends in these results to both diffu sion controlled and shrinkage driven pore growth. (C) 1997 Acta Metall urgica Inc.