Hot compression of nickel with harmonic structure

It is well known that grain size is an important element that affects the mechanical properties of materials, therefore grain refinement strengthening is of extremely high interest. However, materials with an homogeneous nano or ultrafine grained structure show, together with high strength, limited ductility due to their plastic instability. The “harmonic microstructure” is born with the aim of improving the combination of strength and ductility. Harmonic microstructure is obtained with a peculiar ball milling process on different pure metals and alloys. In the present paper, harmonic structured nickel is presented and in particular its behavior under compression at high temperature was investigated for the first time. Stress-strain curves were recorded and compression resistance evaluated at different temperatures. A “conventional” not harmonic microstrctured nickel was tested as comparison in the same conditions. The characteristics of the harmonic structure after hot compression were analyzed through metallographic analysis.