Mechanical properties of A17075 alloy with nano-ceramic oxide dispersion synthesized by mechanical milling and consolidated by equal channel angular pressing

摘要

An Al-alloy matrix composite with a dispersion of nano-TiO_2 has been synthesized in powder form by mechanical milling of pre-alloyed A17075 alloy and nano-TiO_2 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 A17075 alloy with nano-TiO_2 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 (≈1.7 GPa). Conspicuously the above properties are independent of structural orientation as texture analysis shows almost random texture even after ECAP consolidation.