Mechanical properties of Al7075 alloy with nano-ceramic oxide dispersion synthesized by mechanical milling and consolidated by equal channel angular pressing

An Al-alloy matrix composite with a dispersion of nano-TiO2 has been synthesized in powder form by mechanical milling of pre-alloyed Al7075 alloy and nano-TiO2 powder blend. XRD and TEM analyses of the milled powder confirm the particle/crystallite size in nanometer range. The composite powder was consolidated by equal channel angular pressing (ECAP) at ambient temperature and 473 K at a speed of 5 mm/min. Microstructural analysis of consolidated compacts of Al7075 alloy with nano-TiO2 dispersion was carried out using both scanning and transmission electron microscopy. The compacts prepared by ECAP possess reasonably good density (90% of theoretical density), excellent hardness (3.72 GPa/344 VHN) and high stiffness (Young's modulus of 92 GPa). Furthermore, the compacts consolidated by 4 ECAP passes at 473 K exhibit, beside the highest density, an extremely high compressive strength (approximate to 1.7 GPa). Conspicuously the above properties are independent of structural orientation as texture analysis shows almost random texture even after ECAP consolidation. (C) 2012 Elsevier B.V. All rights reserved