Atom Probe Tomography of Solute Distributions in Mg-Based Alloys

Abstract

Atom probe tomography (APT) has been carried out on three magnesium-based alloys: M1 (Mg-1 wt pct Mn), AZ31(Mg-3 pct Al-1 pct Zn), and ME10 (Mg-1 pct Mn-0.4 pct misch metal). The aims of this experiment were to measure the composition of the matrix and to investigate solute clustering in the matrix of the three different alloys. For AZ31, the matrix composition was variable but close to the bulk composition. For ME10 and M1, the matrix was depleted in alloying additions, with the remainder residing in precipitates. Most alloying additions were found to exhibit clustering to some extent, with misch metal having the strongest partitioning behavior to clusters. Solute clusters did not appear to affect mechanical twinning. It has been proposed that the clustering behavior of misch metal contributes to its ability to modify the recrystallization texture.

Role of Solute in the Texture Modification During Hot Deformation of Mg-Rare Earth Alloys

“…Variability in the level of segregation observed between various experiments is attributed to solute clustering, which is consistent with recent atom probe measurements. [67] Static annealing reveals slow grain growth suggestive of low grain boundary mobility in the presence of slow diffusing grain boundary solute. The most concentrated alloy exhibits a limiting grain size indicative of a Zener pinning-type effect, attributed to the previously mentioned solute clusters, since no precipitation is expected.…”

“…In a recent atom probe tomography study of Mgalloys, [67] it was discovered that RE atoms strongly partition to clusters. Furthermore, a possible link between clustering and grain boundary segregation was suggested, although no grain boundary interrogation was performed.…”

“…It has been suggested that solute clusters could induce an effect akin to Zener pinning, [74] and strong RE solute clustering has been observed in misch metal containing Mg alloys with even lower RE concentrations. [67] E. Continuous DRX Continuous [71] (or rotation [75] ) DRX involves the progressive rotation of subgrains formed during deformation until their boundary misorientations are indistinguishable from those of the original high-angle grain boundaries. [76][77][78] In many ways, continuous DRX is simply a recovery mechanism, and dislocation climb and/or cross-glide are necessary for dislocations to rearrange themselves into cell and subgrain boundaries.…”

Microstructural evolution during hot shear deformation of an extruded fine-grained Mg–Gd–Y–Zr alloy

“…Thus, the RE elements usually segregate at grain boundaries [14,34,35] and dislocations [36], dissolve in the Mg-matrix and/or form clusters in the interiors of the grains [37] in addition to forming RE-rich particles. Accordingly, due to the low diffusion rates of these elements in magnesium, the RE elements may retard recrystallization so that higher temperatures are required for the onset of recrystallization in RE-containing Mg alloys.…”

Estimating the physical cluster‐size distribution within materials using atom‐probe

“…It is arguably the best approach available for direct imaging of atomic cluster dispersions. Atomic clustering of solute atoms within multi-component solid solutions is of both scientific and technological interest as solute clusters influence the decomposition's nature and the physical properties of the solid solution (Aruga et al, 2009;Radiguet et al, 2008;Ringer, 2006;Stanford et al, 2009).…”