The application of magnesium flat products is affected by the limited formability at room temperature and the anisotropy of the mechanical properties. The main reason for this is the underlying hexagonal crystal structure of magnesium and the development of strong crystallographic textures during massive forming processes with distinct alignment of basal planes. For an improvement in the properties of semi-finished products, the detailed knowledge of the influence of the manufacturing process on the microstructure and texture evolution of the flat products as a result of dynamic and static recrystallization is required. In this work, flat products made of conventional magnesium alloy AZ31 were manufactured by the rolling process as well as by direct extrusion, with variation in the process temperature. This allowed the development of a distinct variation in microstructures and textures of the flat products. The effects on mechanical properties and formability are highlighted and discussed in relation to the microstructure and texture. It is shown that both the process and the temperature have a major influence on texture and consequently on the material properties.
The microstructural characteristics of biodegradable Mg alloys determine their performance and appropriateness for orthopedic fixation applications. In this work, the effect of the annealing treatment of a Mg-0.7Zn-0.6Ca (ZX11) alloy on the mechanical integrity, corrosive behavior, and biocompatibility-osteoinduction was studied considering two annealing temperatures, 350 and 450 °C. The microstructure showed a recrystallized structure, with a lower number of precipitates, grain size, and stronger basal texture for the ZX11-350 condition than the ZX11-450. The characteristics mentioned above induce a higher long-term degradation rate for the ZX11-450 than the ZX11-350 on days 7th and 15th of immersion. In consequence, the mechanical integrity changes within this period. The increased degradation rate of the ZX11-450 condition reduces 40% the elongation at failure, in contrast with the 16% reduction for the ZX11-350 condition. After that period, the mechanical integrity remained unchanged. No cytotoxic effects were observed for both treatments and significant differentiation of mesenchymal stem cells into the osteoblast phenotype was observed.
In this work, the microstructure and texture of Mg-1.0Al-xZn-0.2Mn-0.5Ca (wt.%, x = 0, 1) alloys, which were produced via conventional casting or twin roll casting (TRC), were investigated, and their relation to the mechanical properties of the sheets at the final gage was analyzed. In the Zn-containing AZMX1100 alloy sheets, the amount and size of the secondary phases were significantly reduced, in comparison to the Zn-free AMX100 alloy sheet. The TRC sheet shows a smaller grain structure and fine secondary phases in comparison to the sheets produced via the conventional casting process. The texture of the AMX100 sheet is characterized by the basal poles tilted in the sheet rolling direction (RD). In the AZMX1100 sheets, the texture with the tilted basal poles towards the RD and transverse direction (TD) was developed after recrystallization annealing, while the tilting angle of the basal pole in the TD is larger than in the RD. There is no significant difference in the texture between the sheets produced by the casting and TRC process. The highest yield strength was obtained in the AZMX1100 sheet produced by the TRC process, and all examined sheets showed the mechanical anisotropy in accordance with their textures.
An understanding of deformation behavior and texture development is crucial for the formability improvement of Mg alloys. X-ray line profile analysis using the convolutional multiple whole profile (CMWP) fitting method allows the experimental determination of dislocation densities separately for different Burgers vectors up to a high deformation degree. A wider use of this technique still requires exploration and testing of various materials. In this regard, the reliability of the CMWP fitting method for Mg–Zn–Y alloys, in terms of the dislocation activity during tensile deformation, was verified in the present study by the combined analysis of electron backscatter diffraction (EBSD) investigation and visco-plastic self-consistent (VPSC) simulation. The predominant activity of non-basal 〈a〉 dislocation slip was revealed by CMWP analysis, and Schmid factor analysis from the EBSD results supported the higher potential of non-basal dislocation slip in comparison with basal 〈a〉 dislocation slip. Moreover, the relative slip activities obtained by the VPSC simulation also show a similar trend to those obtained from the CMWP evaluation.
This paper will give an overview about the development of a material system, which consists of a novel formable magnesium alloy that is provided with an effective corrosion protection coating. The corrosion protection is to be realized in the form of a forming stable powder coating, which can be applied in the coil coating process. To improve the tribological properties, additional additives are added to the powder coating. Within this paper, first results concerning tribological and forming behavior of the new lightweight material system are given. For the benchmark, the results are compared with commercially available AZ31 Mg alloy.