Influence of ceramic nanoparticles on grain growth in ultra fine grained copper prepared by high pressure torsion
Abstract
Bulk ultra-fine grained (UFG) materials with no residual porosity can be produced by high pressure torion (HPT). A number of UFG metals exhibit improved mechanical properties consisting in a favourable combination of very high strength and a reasonable ductility.
Unfortunately, the thermal stability of UFG structure is rather low. Recrystallization takes place at elevated temperatures and the superior mechanical properties are lost.
Thus, it is highly desirable to improve the thermal stability of UFG structure. In the present work we studied the thermal stability of UFG Cu containing Al2O3 nanoparticles.
The aim of this work was to check whether the ceramic nanoparticles can inhibit grain growth and, thereby, to extend the thermal stability of UFG structure. We have found that the HPT deformed samples exhibit UFG structure with grain size around 150 nm and a high density of dislocations situated mainly in distorted layers along grain boundaries.