Tensile properties of mechanically alloyed Al-Nb alloy and Al-Al_3Nb composites extrusions

摘要

Tensile behavior of mechanically alloyed(MA) Al-5wt.%Nb alloy extrusion was examined at various temperatures andstrain rates. The tensile ductility of MA Al-5wt.%Nb alloyextrusion was greatly reduced with increasing temperature and/ordecreasing strain rate. The SEM observations of side and fracturesurfaces of tensile fractured specimens demonstrated that theoverall void density formed during deformation was considerablyreduced, along with the sign of decreased plasticity around thedimples on the fracture surface. To understand the effect of grainsize on the deformation behavior of submicron grain sized alloys,Al-5 vol.%Al_3Nb composite extrusions with different grain sizeswere fabricated and tensile tested at different temperatures. Thepresent study confirms that the reduction in tensile ductility ofsubmicron grain sized alloys at elevated temperatures areundoubtedly related to the grain size. Fast dynamic recovery rates,due to the lack of dislocation substructures, in submicron grainsized alloys appears to be responsible for the elevated temperaturereduction in tensile ductility.