MECHANICAL PROPERTIES AND MICROSTRUCTURES OF TWIN ROLL CAST Mg-2.4Zn-0.1Ag-0.1Ca-0.16Zr ALLOY

In our previous study, we reported that the additions of 0.1 at.% Ag and 0.1 at.% Ca to Mg-2.4Zn-0.16Zr ( at.%) alloy enhanced the age hardening response, and extruded alloy showed tensile yield strength of 325 MPa with the T6 heat treatment. Considering its excellent age hardenability, we attempted to develop high strength sheets from the alloy by twin-roll casting (TRC). TRC sheet of 2 mm in thickness were hot rolled to similar to 1.2 mm. The TRC Mg-2.4Zn-0.1Ag-0.1Ca-0.16Zr alloy sheet showed tensile yield strength of similar to 320MPa and an elongation to failure of 17% after T6 heat treatment. EBSD study indicated the average grain size is similar to 18 +/- 2.5 mu m and the grains have a weak basal texture. TEM, showed a uniform distribution of similar to 5 nm diameter MgZn2 phase. The high yield strength was attributed to the dispersion of rod-like precipitates.