Development of amorphous phase dispersed Al-rich composites by rolling of mechanically alloyed amorphous Al-Ni-Ti powders with pure Al

Abstract

Mechanical alloying of Al-rich Al-Ni-Ti elemental powder blends by planetary ball milling up to 50 h yields amorphous and/or nanocrystalline products. Among the different alloys synthesized by mechanical alloying, Al₈₀Ni₁₀Ti₁₀ yields a predominantly amorphous product, while the others develop a composite microstructure comprising nanaocrystalline and amorphous solid solutions. In order to consolidate milled amorphous/nanocrystalline powders into bulk solid form, the amorphous Al₈₀Ni₁₀Ti₁₀ alloy is mixed with different amounts of Al powder, consolidated within Al-cans by 7 GPa pressure and subjected to rolling into 2-5 mm thick sheets with/without intermediate annealing for 10 min at 500 K. The composite sheets so formed with an optimum amount of amorphous phase dispersion record a significant (2-2.5 times) improvement in hardness compared to that of pure Al.