Controlled diffusion solidification - Manufacturing net shaped al-based wrought alloy parts

Aluminum based wrought alloys combined with differing percentages of other metals such as silicon, copper, magnesium, and manganese form alloys that are used in many domestic, automotive and aerospace applications. Net shape manufacturing of wrought alloys (via casting) has been difficult due to the tendency of these alloys to form "hot tears". Hot tearing tendency coupled with coherency temperature that is close to the liquidus temperature lead to the development of cracks in the final "as cast" structure. The microstructure of wrought alloys is predominantly dendritic, and by altering the dendritic morphology to a globular one (providing a continuous interdendritic liquid network) one can considerably reduce the hot tearing issue. A novel method has been developed at WPI, termed Controlled Diffusion Solidification or CDS to allow casting of wrought alloys. In this process, two precursor alloys of precisely controlled composition and temperature are mixed to produce a predetermined alloy composition. CDS provides an alternate route for net shape manufacturing of wrought alloys and otherwise difficult to cast casting alloys. In this paper, CDS process is presented with results from laboratory and industrial trials. The laboratory trails include a mix of Al based wrought alloys and cast alloys. The industrial trail was limited to the 2xxx (Al-Cu) series.