LUE - Développement de composites métalliques nano-structurés à base de céramiques dérivées de polymères pour des applications durables en recyclage et santé

Keywords

Severe Plastic Deformations, process, microstructures, textures, metal composites

Subject details

This proposal is based on a long standing very active collaboration between the LEM3 laboratory of the University of Lorraine and the Materials Science as well as the Mechanical Engineering Departments of the Indian Institute of Science (IISc, ranked number one university in India). The scientific objective of the project is to produce bulk metallic sheets from powder in a single step. The consolidation processing of powder Al, Mg, Cu & Ti metals will be carried out using a newly developed severe plastic deformation technique for producing nanostructured high-strength metal in a single operation step. The problems with existing powder processing technologies are (a:) not able to produce the final component in a single step, so multistep processing becomes energy intensive and hence economically less viable, (b:) the requirement of high-temperature processing induces undesirable phase changes, grain growth issues, consumes more energy, and (c:) the upscaling for industry of newly proposed bottom-up processes have not been realized. Recently, a new SPD process, known as FALEP (Friction-assisted lateral extrusion process), has been developed in the LEM3 laboratory of the Lorraine University in Metz, France. This technique can produce sheets from billets and can impose extremely large shear strains (up to 200) in a single step. The amount of deformation induced in this process is so high that the grain fragmentation process reaches its saturation state, so the maximum strength of the produced material is reached. Further, microstructure homogeneity is maintained throughout the sample. The advantage of the process is to produce long sheets and readily scalable for industrial production. A recently jointly patented metallurgical process will be applied to improve yield strength without significant loss of ductility and thermal stability of the produced final nanostructured metal. This patent uses simple polymer material mixed with the metal powder then converted into nanoceramics by pyrolysis. The sheets produced from powder show improved strength as compared to sheets produced from bulk billet. A modified version of the FALEP technique, known as cyclic FALEP, is being developed at the Indian Institute of Science, Bangalore, India, the partner of this proposal. Preliminary results have shown that the properties of the sheet can be controlled by varying the processing frequency. At higher frequency processing there is temperature increase in the sample, which reduces the energy needed for the processing, and can eliminate post heat treatments of the material, thus, further reducing the total energy needed. Therefore, the present investigation is focusing on producing bulk sheets from powder in a single step and control the properties of the sheets by controlling the frequency of processing. The work aims to produce bulk nanostructured sheets of aluminum, magnesium, copper and titanium at their highest strength from their respective powders.