First-principles study of coherent interfaces of Laves-phase MgZn2 and stability of thin MgZn2 layers in Mg-Zn alloys

Abstract

The β 1 ′and β 2 ′ are important precipitates in Mg-Zn alloys. Two types of precipitates both are composed of MgZn 2 , but the orientation relationships of MgZn 2 with the α-Mg matrix in two precipitates are different. To understand the properties of β 1 ′and β 2 ′, we use the first-principles method to perform a systematical investigation of coherent interfaces of β 1 ′/α-Mg and β 2 ′/α-Mg. Here, we present exhaustive analysis of the structure and stability for these interfaces, and find that the interfacial energy is highly dependent on the average coordination of interfacial structures. Furthermore, we find that the MgZn 2 slab in matrix with [11 0] MgZn2 //[0001] α , (0001) MgZn2 //(11 0) α orientation relationship (OR1) is less stable than that with [11 0] MgZn2 //[10 0] α , (0001) MgZn2 //(0001) α orientation relationship (OR2), which can explain that the β 2 ′ plate shape precipitates that are frequently observed in Mg-Zn alloys comply with OR2 instead of OR1.

Simultaneously Enhanced Mechanical Properties and Damping Capacities of ZK60 Mg Alloys Processed by Multi-Directional Forging

“…The selected area electron diffraction (SAED) proves that these particles are MgZn 2 (Fig. 3b and c), which has been widely reported in the previous studies [25,26]. The appearance of fine MgZn 2 phase is related to the dynamic precipitation during the reduplicative MDF process, because the homogenization treatment easily results in the supersaturation state of Zn elements in α-Mg matrix.…”

Editors' Choice—Dealloying of MgZn2Intermetallic in Slightly Alkaline Chloride Electrolyte and Its Significance in Corrosion Resistance

“…The covalent, ionic and metallic bonding characteristics of the MgZn 2 phase have been discussed by several authors. 41,42 Much of the pioneering work on the dealloying of binary alloys has focused on alloys of noble elements and the Zn-Cu system. The importance of elemental composition on the critical potential, E c , for the dealloying of binary alloys has been suggested by different authors.…”

Effects of Extrusion on Mechanical and Corrosion Resistance Properties of Biomedical Mg-Zn-Nd-xCa Alloys

“…The lattice constants are a = b = 0.5221 nm, c = 0.8567 nm, α = β = 90°, γ = 120°, and the total number of atoms in the unit cell is 12. Related studies have shown that MgZn 2 phase was a common Mg-Zn strengthening phase, which played an important role in improving the mechanical properties of magnesium alloys [32].…”