Shigeru Kuramoto

High Strength and High Uniform Ductility in a Severely Deformed Iron Alloy by Lattice Softening and Multimodal-structure Formation

Despite high strength of nanostructured alloys, they usually exhibit poor uniform ductility. For many applications, it is an important issue to design new nanostructured alloys which have both high strength and high uniform ductility. In this study, an Fe–Ni–Al–C alloy with ultrahigh tensile strength of 1.9–2.2u2005GPa and high uniform ductility of 16–19% was developed by concurrent employment of several strategies: (i) appropriate choice of chemical compositions for lattice softening, (ii) severe plastic deformation using the high-pressure torsion method for grain refinement, and (iii) control of strain level for multimodal-structure formation composed of equiaxed nanograins, lamellar coarse grains and fine precipitates.

Effect of Alloying Elements on Anneal-Hardening Behavior of Aluminum Alloy Foils

We observed that non-heat treatable Al–Fe–Mn alloy foils exhibit an increase in strength and a decrease in elongation due to low temperature annealing treatment subsequent to cold rolling. In this study, we investigate the effects of alloying elements on this anneal-hardening behavior. The alloys without alloying element of iron were not hardened by low temperature annealing treatment. On the other hand, the anneal-hardening behavior was observed only in Al–Fe based alloys containing manganese or chromium. These results are similar to “hardening by annealing” reported on severe plastic deformation of metal.