Al–(L12)Al3Ti nanocomposites prepared by mechanical alloying: Synthesis and mechanical properties

The present paper reports the formation of nanocomposites containing α-Al and L12–Al3Ti in binary Al–Ti alloys containing 5, 10, 15, and 20 at.% Ti. Supersaturated solid solution of Ti in Al was observed after 20 h of mechanical alloying irrespective of the Ti content. Nanocomposites formed after mechanical alloying and subsequent annealing at 673 K for 2 h showed a high hardness (3.4 GPa), modulus (106.4 GPa) and density (95%). Hardness values of Al–(L12)Al3Ti nanocomposites obtained by nanoindentation were similar to hardness measured with microhardness. High strength of the nanocomposites was attributed to the formation of large volume fraction of nanocrystalline L12–Al3Ti particles and the ultrafine grain size of α-Al matrix.