Microstructure and strength of two alloys Mg 95 Zn 4.2 Y 0.8 and Mg 92.5 Zn 6.5 Y containing icosahedral phase have been studied after extrusion at 250°C and 400°C. Due to its high symmetry and quasiperiodicity, the icosahedral phase can form strong interfaces with the matrix in various orientations. The icosahedral phase particles have a strong pinning effect on the grain boundaries that stabilizes grain size. They are resistant to coarsening, and remain hard at higher temperatures, imparting good strength with ductility at 200°C. Very few deformation structures such as high dislocation density and twins are observed after extrusion or tensile tests. c -type dislocations are commonly observed, which has important implications for greater ductility. Due to the stability of microstructure, various post-extrusion treatments are possible.
ASJC Scopus subject areas
- Condensed Matter Physics