Order/disorder in electrodeposited aluminum-titanium alloys

G.R. Stafford, T. Tsuda, C.L. Hussey
2003 Journal of Mining and Metallurgy. Section B: Metallurgy  
The composition, morphology, and crystallographic microstructure of Al-Ti alloys electrodeposited from two different chloroaluminate molten salt electrolytes were examined. Alloys containing up to 28 % atomic fraction Ti were electrodeposited at 150 °C from 2:1 AlCl 3 -NaCl with controlled additions of Ti 2+ . The apparent limit on alloy composition is proposed to be due to a mechanism by which Al 3 Ti forms through the reductive decomposition of [Ti(AlCl 4 ) 3 ] -. The composition of Al-Ti
more » ... ys electrodeposited from the AlCl 3 -EtMeImCl melt at 80 °C is limited by the diffusion of Ti 2+ to the electrode surface. Alloys containing up to 18.4 % atomic fraction Ti are only obtainable at high Ti 2+ concentrations in the melt and low current densities. Alloys electrodeposited from the higher temperature melt have an ordered L1 2 crystal structure while alloys of similar composition but deposited at lower temperature are disordered fcc. The appearance of antiphase boundaries in the ordered alloys suggests that the deposit may be disordered initially and then orders in the solid state, subsequent to the charge transfer step and adatom incorporation into the lattice. This is very similar to the disorder-trapping observed in rapidly solidified alloys. The measured domain size is consistent with a mechanism of diffusion-controlled domain growth at the examined deposition temperatures and times. * Certain trade names are mentioned for experimental information only; in no case does it imply a recommendation or endorsement by NIST.
doi:10.2298/jmmb0302023s fatcat:257xi6hrkfhwdcdmppy6xxslqe