Solid solution or amorphous phase formation in Al-Mo alloyed films and their mechanical properties

Abstract

The Al-Mo alloyed films were fabricated by magnetron sputtering. The phase structure of them transformed from fcc solid solution to amorphous and then to bcc solid solution as a function of Mo content in the range of 7.5 at.% ∼47.5 at.%. The thermodynamic mechanism of phase formation was investigated by Miedema model. It was found that the Al-Mo alloyed films prepared by sputtering deposition exhibited stronger amorphous forming ability. The amorphous forming composition range (AFCR) of them was speculated to be within the range of 15 to 47 at.% Mo, based on the Miedema prediction. The study found that the Al-Mo alloyed films with amorphous phase exhibited excellent mechanical properties. The nanoindentation hardness reached 8.73 GPa which was more than triple of the pure Al films even higher the pure Mo films. And the critical strain obtained the maximum value of 2.83% representing the most excellent ductility.