Porosity, hydrogen and bifilm content in Al alloy castings

In Al alloy castings, it is often not microstructure, but entrained defects in the form of bifilms that dominate mechanical properties. To assess their effect, this study targets a new quantification of metal quality, measuring the lengths and number of bifilm defects as determined from the microstructural section of a reduced pressure test (RPT) sample.

Research highlights
► The presence of bifilms in aluminium can be quantified by reduced pressure test.
► Bifilm index can discriminatingly assess aluminium melt quality.
► Number of bifilms is directly related with the number of the pores.
► Metal quality can be quantified by using both bifilm index and number of pores.
► It is predicted that very high ductility will be achieved in the absence of bifilms.