Application of severe plastic deformation for formation of structure and properties of aluminum alloys containing yttrium or mischmetal

aim of project
The scientific aims of the project is fabrication of aluminum alloys characterized by high strength and at the same time satisfactory plasticity and cracking resistance. Such properties should provide nanostructure in aluminum alloys containing yttrium or mischmetal with initial microstructure with a large content of intermetallic phases obtained with severe plastic deformation. After refi nement of microstructure it will contain nanocrystalline dispersions of intermetallic phases within ductile matrix of nanocrystalline aluminum. There is a need to develop a method of fabrication of materials characterized by high tensile strength and high microhardness and at the same time suffi ciently high ductility needed for constructional materials. Such possibility is proved by natural composites e.g. oyster shell. High cracking resistance of this natural material arises from its nanocrystalline structure. Nanocrystalline lamellas of brittle mineral (aragonite) are separated by very thin layers of protein. Small dimensions of lamellas cause that stress concentration does not exceed their theoretical resistance and protein layer prevents transmission of stress on next lamellas. Therefore, there is no stress concentration in the material making it crack.

expected results
By casting and severe plastic deformation, there is a possibility of fabrication of an alloy with the structure consisting of nanocrystalline dispersions of intermetallic phases within the ductile matrix of nanocrystalline aluminum.

This type of nanostructure will allow to achieve high tensile strength with satisfactory plasticity and cracking resistance at the same time.

Substitution of yttrium with a cheaper mischmetal will not affect the mechanical properties of the alloy.