Research project: Processing of a two phase alloy by severe plastic deformation

The grain size of metallic alloys may be refined to the submicrometer level by using processing SPD techniques such as equal-channel angular pressing (ECAP) and high-pressure torsion (HPT). In ECAP the sample is in the form of a bar and it is subjected to repetitive pressing through a special die whereas in HPT the sample is in the form of a disk and it is subjected to an applied pressure and concurrent torsional straining.  Little information is at present available comparing the microstructures and the mechanical properties of two-phase alloys processed using these two techniques. This investigation is designed to make a direct comparison between ECAP and HPT using a typical two-phase alloy and it involves materials processing, mechanical testing and microstructural analysis.

The Pb-62% Sn eutectic alloy is a classic superplastic material exhibiting a record superplastic elongation of 7550%. The reason for this exceptional elongation is that grain growth is restricted by the presence of two separate phases. In this project, the Pb-Sn eutectic alloy is processed with ECAP or HPT or by using a combination of these two methods (ECAP+HPT) and the microstructural characteristics and mechanical properties are then measured.