Effect of Rare-Earth Elements Y and Dy on the Deformation Behavior of Mg Alloy Single Crystals

Abstract

Effect of rare-earth elements (Y and Dy) on the mechanical properties of Mg solid solution single crystal is investigated. Comparing with the effect of other elements reported by previous studies, the solid solution strengthening by Y and Dy are much higher than that of other additives such as Zn for basal slip operation, while the isotropic strain by Zn atoms is higher than those of Y and Dy. Strain-rate changing tests were conducted for a further understanding of the dislocation motion and it revealed that the activation volumes estimated for Mg alloys with Y and Dy are much smaller than that of Zn-added alloy, while the activation enthalpy is almost the same. It was confirmed that the high strengthening effect by Dy addition is also found by Y addition, while the elastic interaction based on neither isotropic or anisotropic distortion are sufficient to explain the origin of the strengthening effect by Y and Dy addition.

Electronic origin of the anomalous solid solution hardening of Y and Gd in Mg: A first-principles study

“…However, recent experimental studies [4,5,15,16] have demonstrated that Y and Gd exhibit anomalously higher solid solution hardening efficiency than those of Al and Zn in terms of the misfit parameters, which cannot be understood using the elastic interaction model. Such anomalous solid solution hardening of other RE elements, such as Ce [17] and Dy [18], was also reported. A few experimental and theoretical studies have been carried out to explore the solid solution hardening of RE in Mg.…”

Effect of rare earth elements on the structures and mechanical properties of magnesium alloys

“…From the calculated theoretical elastic constants of the pure magnesium in Figure 2, it can be seen that the average differences between calculated and experimental data are less than 5%, which guarantee the accuracy of our calculations. As summarized in Figure 2(a) and (e), the addition of REEs results in an increase of c 11 and c 44 from La to Sm, followed by a decrease trend from Gd to Tm with abnormal low value at Eu and Yb, while c 12 , c 13 and c 33 in Figure 2 In order to examine the effect of doping concentration of rare earth elements, we substituted two RE atoms for Mg atoms in the supercell and obtained the Mg 52 RE 2 alloys. Thus, the concentration of rare earth elements increased to 1/27.…”

“…It is interesting that though the atomic size factor of Gd and Y is smaller than that of Al and Zn, they improve the mechanical properties more effectively than Al and Zn, according to Akhtar et al [9] and Gao et al [10]. Analogous phenomenon exists in Mg-Dy and Mg-Y alloys [11]. Gao et al [10] give an explanation of the anomalous hardening of Mg-Y and Mg-Gd alloy from the view of the increase of chemical bonding strength.…”

Deformation Response of Mg-Y Alloys under Dynamic Loading

“…It has been reported that addition of rare earth elements such as yttrium may improve mechanical properties over conventional Mg-Al-Zn alloys by minimizing intensity of the basal texture [5][6][7][8][9]. However, the deformation behavior of Mg alloys containing yttrium is not sufficiently understood at strain rates exceeding 1×10 3 s -1 .…”

“…It has also been reported that a Mg-Al-Mn alloy had pronounced mechanical anisotropy at high strain rates of around 1.0×10 3 s -1 [4]. Therefore, the mechanical properties of Mg alloys should be evaluated accurately for applications involving possible dynamic loading.It has been reported that addition of rare earth elements such as yttrium may improve mechanical properties over conventional Mg-Al-Zn alloys by minimizing intensity of the basal texture [5][6][7][8][9]. However, the deformation behavior of Mg alloys containing yttrium is not sufficiently understood at strain rates exceeding 1×10 3 s -1 .…”