Effect of Ca Precipitation on Texture Component Development in AZ Magnesium Alloy

Abstract

To enhance the formability of magnesium alloys, inhibition of basal texture development by the particle-stimulated nucleation (PSN) effect has attracted significant interest. However, its contribution to texture development is not easily observed due to the separation of texture from the conventional deformation behavior. This study aims to separate the Ca texture from the deformation behavior of AZX611 alloy and quantify it using scanning electron microscopy with electron backscatter diffraction (SEM-EBSD). Since Ca in the AZ61 magnesium alloy precipitated as Al2Ca, the hot-rolled magnesium alloys AZ31, AZ61, and AZX611 were used. High temperature compression was conducted at 723 K, the strain rate 0.05/s and 0.005/s and the true strain up to −1.0. Dynamic recrystallization was observed in each specimen and the Ca-free alloys showed dislocation glide at high strain rates and solute drag at low strain rates. When the dislocation glide dominated, basal texture was strengthened. In contrast, solute drag caused non-basal texture development. Precipitation hardening caused AZ61 to have higher flow stress than those of the Ca-free alloys by the PSN effect; its texture was observed separately because the PSN grain growth around the precipitation and orientation was specific, similar to the one developed at the solute atom drag.

Effect of Al Concentration on Basal Texture Formation Behavior of AZ-Series Magnesium Alloys during High-Temperature Deformation

“…This difference in the Taylor factor on each grain rolled is a factor determining which grains would consume others or would be diminished. From the many results on the factors affecting dislocation movement, such as the strain rate in the AZ31 alloy [ 29 ] or precipitation in the AZX611 [ 13 ] magnesium alloy, a similar phenomenon was observed.…”

“…According to the von Mises theory, magnesium alloys require the activation of at least five or more independent slip systems to accompany the deformation [ 13 ]. However, magnesium alloys are generally deformed by basal slip systems, and the lack of slip systems becomes the major problem of formability.…”

“…However, according to its phase diagram, the Mg 17 Al 12 phase in the AZ91 alloy is decomposed at a temperature of 643 K, and its decomposition temperature decreases as the composition reaches that of pure Mg [ 25 ]. Moreover, the thermal properties of precipitation phase such as Mg 17 Al 12 have been already investigated in our previous study [ 13 , 26 ]. In particular, the results were obtained through the differential scanning calorimetry (DSC) method, using the AZ61 alloy and AZX611 alloy.…”

“…Moreover, one of authors has investigated the effect of Ca precipitation on the texture development of AZ magnesium alloys. [ 13 ] Through the results, the AZ series magnesium alloy showed that the higher Al content made them have a more-sharpened basal texture. In addition, the basal texture formation behavior was shown more sharply in AZ61 than that of AZ31 [ 14 ].…”

Effect of Recrystallization Behavior of AZ31 Magnesium Alloy on Damping Capacity

“…Considering that these factors are influenced by the activity of dislocations, they can also affect the damping performance. Furthermore, authors have investigated the distribution of dislocation density using the Kernel average misorientation map [ 16 ]. Through them, the annealing process or deformation in high temperature environment made the dislocation density to be changed.…”