Rheo-casting of Al based wrought and cast alloys via controlled diffusion solidification

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CDS is a novel rheo-casting process to facilitate the net shaped castings of Al based wrought and cast alloys by Controlled Diffusion Solidification. The objectives of the first phase of this project were achieved and the knowledge base for the mechanisms involved in CDS and the control required on the processing parameters have been successfully developed. CDS as a process has also attracted significant interest from the automotive sector and specific projects to develop novel alloys for automotive parts have been initiated. The proposed second phase of this project will pursue the development of specific alloy chemistries and the process parameters required to process these alloys. Specific aluminum wrought alloys from the 2xxx, 3xxx, 4xxx, 5xxx, 6xxx and 7xxx alloy series will be developed for the the CDS process and cast into net shaped components and their mechanical and performance properties quantified. Two main processes will be used for this study: high pressure/squeeze die casting and tilt pour permanent mould casting. The process parameters identified as critical in the first phase of this project are melt superheats for the two precursor alloys, mass ratio of mixing, rate of pour of second alloy into the first alloy, wait time prior to casting the mixed alloy, mould pre-heat temperature. Each final desired alloy chemistry has a specific windows of operation for each and every process parameter mentioned above. The objectives of the proposed research program include the design and development of individual precursor alloys and optimize the above mentioned process parameters. The alloys being developed are specifically from 2xxx, 3xxx, 4xxx, 5xxx, 6xxx and 7xxx families of Al wrought alloys. The specific tasks are to quantify the effect of pouring method and rate of second alloy on the resultant microstructure and properties, optimize process conditions for high pressure/Squeeze die casting and tilt pour permanent mould casting processes for CDS, develop a guide book to present the specific detailed instructions on the procedure to cast various alloys by CDS, and evaluate mechanical properties such as Tensile, Fatigue, Creep and Wear for all the alloys being cast.