화학공학소재연구정보센터
Journal of Materials Science, Vol.55, No.8, 3588-3604, 2020
The effect of Zn/Ca ratio on the microstructure, texture and mechanical properties of dilute Mg-Zn-Ca-Mn alloys that exhibit superior strength
The microstructure, texture and mechanical properties of a series of Mg-Zn-Ca-Mn alloys with three Zn/Ca ratios (2.63, 1.22 and 0.53, by weight ratio) were investigated. The dominant second phase changed from MgZn to Ca2Mg6Zn3 as the Zn/Ca ratio decreased from 2.63 to 1.22. With decreasing Zn/Ca ratio, the grain size of the as-cast alloys was significantly decreased, accompanied by an increase in the volume fraction of second phase.For as-extruded Mg-1.4Zn-2.6Ca-0.5Mn, the finest (similar to 0.36 mu m) recrystallized grain structures, containing both fine MgZn2 precipitates and alpha-Mn particles, were obtained at an extrusion speed of 0.01 mm/s. The texture of the deformed structure was more intense (similar to 30.39 mud) relative to the recrystallized region (similar to 8.33 mud). As the Zn/Ca ratio decreased, basal plane texture was weakened deriving from grain refinement following recrystallization. Superior mechanical properties with a yield strength of similar to 387.8 MPa and ultimate tensile strength of similar to 409.2 MPa were achieved in the Mg-1.4Zn-2.6Ca-0.5Mn alloy extruded at 270 degrees C at an extrusion speed of 0.01 mm/s. A number of factors were determined to contribute to strengthening including Hall-Petch effects from the fine recrystallized grains (contribution similar to 58.7%), dislocation strengthening of the deformed region (contribution similar to 29.3%) and Orowan strengthening (contribution similar to 12%).