Interdiffusion and atomic mobility in hcp Mg–Al–Sn alloys

An Effective Strategy to Maintain the CALPHAD Atomic Mobility Database of Multicomponent Systems and Its Application to Hcp Mg–Al–Zn–Sn Alloys

“…Figure 8 and Figure 9 also show the model-predicted composition–distance profiles of 10 diffusion couples (i.e., Mg/Mg-2.77Al-0.97Sn, Mg-1.46Sn/Mg-3.81Al, Mg-0.96Al-1.48Sn/Mg, and Mg-0.98Sn/Mg-1.92Al, annealed at 773 K for 6 h, in at.%; Mg-2.63Al-0.94Sn/Mg, Mg-1.43Sn/Mg-3.80Al, and Mg-1.89Al/Mg-0.97Sn, annealed at 723 K for 9 h, in at.%; Mg/Mg-1.43Al-0.92Sn, Mg-1.45Sn/Mg-3.74Al, and Mg-0.98Sn/Mg-1.83Al, annealed at 823 K for 3 h, in at.%) according to the present atomic mobilities and also those from Zhong et al [ 32 ] compared with the experimental data by Zhang et al [ 34 ]. As can be seen in Figure 6 , Figure 7 , Figure 8 and Figure 9 , the model-predicted composition–distance profiles according to the present work are in better agreement with the experimental data by Zhou et al [ 37 ] and Zhang et al [ 34 ] than the model-predicted ones due from Zhong et al [ 32 ], especially in the figures, i.e., Figure 6 a,b, Figure 7 a,b, Figure 8 b,d and Figure 9 b,c,e,f. Furthermore, the model-predicted diffusion paths at 673, 723, 773, and 823 K, based on the presently updated atomic mobilities and also those by Zhong et al [ 32 ], are displayed in Figure 10 compared with the experimental data from Zhou et al [ 37 ] and Zhang et al [ 34 ].…”

“…For the hcp Mg–Al–Sn ternary system, Zhou et al [ 37 ] determined the composition–distance profiles at 673 and 723 K based on the diffusion couple technique. Moreover, the composition–distance profiles for the Mg–Al–Sn ternary diffusion couples at 723, 773, and 823 K were determined by Zhang et al [ 34 ], respectively. The experimental data from both Zhou et al [ 37 ] and Zhang et al [ 34 ] were employed in the present optimization.…”

“…Moreover, the composition–distance profiles for the Mg–Al–Sn ternary diffusion couples at 723, 773, and 823 K were determined by Zhang et al [ 34 ], respectively. The experimental data from both Zhou et al [ 37 ] and Zhang et al [ 34 ] were employed in the present optimization.…”

“…For the hcp Mg–Al–Sn ternary system, the interdiffusion coefficients (i.e., , , , and ) at the intersection compositions along diffusion paths were determined by Zhou et al [ 37 ] also using the W–G method. Moreover, the inter-diffusivities of the hcp Mg–Al–Sn system were also determined by Zhang et al [ 34 ] by means of the M–K method. As indicated above, all the related interdiffusion coefficients in ternary systems were not used in the assessment procedure but employed to validate the finally obtained atomic mobilities.…”

“…Moreover, the composition–distance profiles in one hcp Mg–Al–Zn–Sn quaternary diffusion couple measured by Bryan et al [ 33 ] can only be used to validate the simulation results but cannot be employed in the optimization process of Zhong et al [ 32 ] due to the limitations of the traditional approach. Furthermore, Zhang et al [ 34 ] measured the new composition–distance profiles of the hcp Mg–Al–Sn ternary system at elevated temperatures recently, which should be considered during the update of the atomic mobility database of the hcp Mg–Al–Sn system.…”