Hydrostatic extrusion and nanostructure formation in an aluminium alloy

A hydrostatic extrusion method was used to obtain nanostructure in an Al-Cu-Mg-Mn aluminium alloy. The material in the form of 20 mm diameter rod was subjected to the hydrostatic extrusion under high pressure. The final diameter was 3 mm. Microstructure observations by transmission electron microscope have revealed the grain refinement down to nanometer scale. Quantitative analysis of the grain size measurements resulted in the mean equivalent diameter of 84 rim. Microhardness measurements suggest that the microstructure is homogenous on the cross section of the rod. Results of tensile tests indicate also significant increase in the flow stresses.