A comprehensive diffusion mobility database comprising 23 elements for magnesium alloys

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

“…The model-predicted composition–distance profiles of four diffusion couples (i.e., Mg-9.08Al/Mg-2.55Zn at 673 K for 8 h, Mg/Mg-0.87Al-1.12Zn at 673 K for 24 h, Mg-9.10Al/Mg-2.03Zn at 723 K for 4 h, and Mg-2.77Al/Mg-1.06Zn at 723 K for 5 h, in at.%) according to the present atomic mobilities (solid lines) are displayed in Figure 2 , compared with the corresponding experimental data (in symbols) by Kammerer et al [ 35 ]. The model-predicted results by Zhong et al [ 32 ] are also superimposed as dashed lines in the figure for direct comparison with the present results. Without specification, all the model-predicted results of Zhong et al [ 32 ] are taken exactly from their original publication.…”

“…In this paper, the atomic mobilities of three boundary binaries (i.e., hcp Mg–Al, Mg–Zn, and Mg–Sn) were directly taken from Zhong et al [ 32 ] and fixed during the subsequent assessment of atomic mobilities in higher-order systems (i.e., hcp Mg–Al–Zn, Mg–Al–Sn, and Mg–Al–Zn–Sn); thus, there was no need to conduct the literature review for those boundary binaries. In the following, all the measured composition–distance profiles in the hcp Mg–Al–Zn, Mg–Al–Sn, and Mg–Al–Zn–Sn systems available in the literature are briefly introduced and are also summarized in Table 1 .…”

“…In addition, the composition–distance profiles in the AZ91 (Mg-9Al-1Zn, in wt.%)/Mg diffusion couple at 663 and 708 K were also determined by Bryan et al [ 33 ]. But Zhong et al [ 32 ] pointed out that the existence of MgO on the surface of the diffusion couples showed a noticeable effect on the interdiffusion between pure Mg and AZ91 in the work of Bryan et al [ 33 ]. Hence, the composition–distance profiles of three groups (i.e., Mg-9.08Al/Mg-2.55Zn, Mg-9.10Al/Mg-2.03Zn, and Mg-2.27Al/Mg-1.06Zn, in at.%) from Kammerer et al [ 35 ] were employed in the present optimization, while the composition–distance profiles from Bryan et al [ 33 ] as well as the composition–distance profiles of Mg-0.87Al/Mg-1.12Zn and diffusion paths from Kammerer et al [ 35 ] were not.…”

“…In order to precisely design the optimal additional amount of Sn in AZ alloys, accurate diffusion coefficients in hcp (hexagonal close-packed) Mg–Al–Sn–Zn alloys are needed. Up to now, the atomic mobilities in the hcp Mg–Al–Zn–Sn quaternary system have only been assessed by Zhong et al [ 32 ] according to the traditional approach. 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.…”

“…Up to now, the atomic mobilities in the hcp Mg–Al–Zn–Sn quaternary system have only been assessed by Zhong et al [ 32 ] according to the traditional approach. 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.…”