Consolidation of Nanostructured Metal Powders Produced by Modulation-Assisted Machining

In the present study, nanocrystalline aluminum alloy (Al3003-H14) particulate produced by modulation-assisted machining (MAM) is consolidated by indirect extrusion. The extrusion die was simultaneously heated below the critical time-temperature conditions for recrystallization. Experimental consolidation of platelet shaped particles showed a distinct elongation of grain size in the primary extrusion direction. Metallographic and transmission electron microscopy observations revealed ultrafine grained microstructure with grains having similar orientations across grain boundaries. The shear from indirect extrusion combined with the uniform distribution of alloy particulates by MAM provides a potential route for bulk consolidation of metals and alloys with ultra-fine grained microstructure.