Evolution of Recrystallized Grain and Texture of Cold-Drawn Pure Mg Wire and Their Effect on Mechanical Properties

Abstract

Static recrystallization plays a key role in the fabrication of thin Mg wires as well as the mechanical properties of the final wires. The effect of annealing parameters on the evolution of the microstructures, textures and mechanical properties of cold-drawn pure Mg wire was studied by means of optical microscopy (OM), electron backscatter diffraction (EBSD), a tensile test and a hardness test. This study shows that the mechanical properties of as-annealed pure thin Mg wire is affected not only by the average grain size, but also the uniformity of the recrystallization grains, including the uniformity of grain size and crystal orientation distribution (more random texture component). With increasing annealing temperature and time, the uniformity of recrystallization grain size first improved and then declined after obvious grain growth. At the same time, the randomness of the basal texture component declined with the development of recrystallization. Annealing at 300 °C for 30 min caused the most uniform grain size and orientation distribution in the microstructures, thus contributing to the best plasticity among all experimental wires. It is reasonable to conclude that more uniform and regular recrystallized grains and a more randomly distributed crystal orientation would be benefit for the mechanical properties of Mg wires.

Development of Novel Lightweight Metastable Metal–(Metal + Ceramic) Composites Using a New Powder Metallurgy Approach

“…Upon application of direct extrusion at 150 °C on the cold compacted material without soaking (B150), dynamic recrystallization occurred at Mg-Zn interface while a few un-recrystallized grains remained as coarse grains [ 24 , 25 , 26 , 27 ]. Recrystallization primarily initiated at various interfaces such as grain boundary [ 28 , 29 ] and interface between dissimilar metals [ 21 , 27 ]. In currently extruded materials, recrystallization could initiate at Mg-Zn interface and Mg grain boundaries during hot extrusion considering that the onset of recrystallization temperature of pure Mg is same as the extrusion temperature, i.e.…”

“…With soaking of the material at 150 °C for an hour before extrusion in B150S sample, similar phenomena seem to happen as the same pattern of fine and coarse grain combination ( Figure 4 a,b) and the same heterogeneous grain distribution ( Figure 4 e,f) was observed. In a study on grain crystallization of pure magnesium [ 29 ], partial recrystallization occurred at homogenization (soaking) temperature of 150 °C. Similarly, it is possible that recrystallization initiated partially even before extrusion upon application of soaking at 150° in B150S sample.…”

“…Whereas, for those with strong texture, twin initiation and propagation was easily accommodated by the preferred basal orientation. Meng et al [ 29 ] reported the presence of weak texture in fine, DRXed grains at the initial stage of recrystallization. Based on the previous studies [ 29 , 43 ], in B150 and B150S, only a few coarse grains accommodated twinning deformation while twinning was obstructed in fine and weakly textured grains during plastic deformation after yielding.…”

“…Meng et al [ 29 ] reported the presence of weak texture in fine, DRXed grains at the initial stage of recrystallization. Based on the previous studies [ 29 , 43 ], in B150 and B150S, only a few coarse grains accommodated twinning deformation while twinning was obstructed in fine and weakly textured grains during plastic deformation after yielding. During the strain hardening stage, plastic flow could continue with slip instead of twinning deformation in fine DRXed grains.…”

Influence of Heat Treatments on the Microstructure and Mechanical Properties of Two Fine Mg–Li–Y Alloy Wires for Bioresorbable Applications

“…[27,28] Studies concerning fine MgRE alloy wires, however, have not shown that recrystallization of the RE texture is achievable in severely cold drawn wires, which is attributed to the high level of deformation imparted on the wires during drawing. [7,8,10,29] This study seeks to investigate the suitability of two Mg-Li-Y alloy wires, with varying Y content, for application in bioresorbable medical devices that undergo high levels of plastic deformation. Li and Y were selected as they are both shown to improve the mechanical properties of Mg and are considered safe in vivo within the alloying limits investigated in this study.…”