Mechanical properties of microalloying Mg-2.2Zn-1.8Ca-0.5Mn(wt%)matrix composites reinforced by 0.5 wt%TiC nanoparticles before and after extrusion were investigated based on the detailed microstructural analysis.A un...Mechanical properties of microalloying Mg-2.2Zn-1.8Ca-0.5Mn(wt%)matrix composites reinforced by 0.5 wt%TiC nanoparticles before and after extrusion were investigated based on the detailed microstructural analysis.A uniform distribution of TiC nanoparticles was realized in the nanocomposite by the method of ultrasonic-assisted semisolid stirring.The morphology of eutectic Ca2Mg6Zn3 phases changed from plate-like in the free TiC nanoparticles region to lamellar in the dense TiC nanoparticles region for the as-cast nanocomposite.Both the grain structure and precipitates were obviously refined as the extrusion temperature decreased from 350 to 270℃.The nanocomposite exhibited excellent tensile yield strength(352-428 MPa)which was governed by the extrusion temperature.The grain refinement strengthening with the contribution ratio of^80%to this strength increment was much higher relative to thermal expansion effect,Orowan strengthening and dislocation strengthening.Ultrafine recrystallized grain structure with a substantial of ne precipitates appeared in the nanocomposite extruded at 270℃.The refined grain structure was not only due to dynamic recrystallization,but also the synergistic pinning effect of nano-TiCp,precipitated MgZn2 and α-Mn particles.The tensile toughness value of nanocomposite after extrusion improved with increasing the extrusion temperature.Massive micro-cracks formed along the remnant coarse Ca2Mg6Zn3 led to the structural failure during tension.展开更多
基金the National Natural Science Foundation of China[grant numbers 51771129,51401144 and 51771128the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi+2 种基金the Scientific and Technologial Innovation Programs of Higher Education Institutions in Shanxithe Natural Science Foundation of Shanxi Province[grant numbers 2015021067 and 201601D011034]the Projects of International Cooperation in Shanxi[Grant no.201703D421039].
文摘Mechanical properties of microalloying Mg-2.2Zn-1.8Ca-0.5Mn(wt%)matrix composites reinforced by 0.5 wt%TiC nanoparticles before and after extrusion were investigated based on the detailed microstructural analysis.A uniform distribution of TiC nanoparticles was realized in the nanocomposite by the method of ultrasonic-assisted semisolid stirring.The morphology of eutectic Ca2Mg6Zn3 phases changed from plate-like in the free TiC nanoparticles region to lamellar in the dense TiC nanoparticles region for the as-cast nanocomposite.Both the grain structure and precipitates were obviously refined as the extrusion temperature decreased from 350 to 270℃.The nanocomposite exhibited excellent tensile yield strength(352-428 MPa)which was governed by the extrusion temperature.The grain refinement strengthening with the contribution ratio of^80%to this strength increment was much higher relative to thermal expansion effect,Orowan strengthening and dislocation strengthening.Ultrafine recrystallized grain structure with a substantial of ne precipitates appeared in the nanocomposite extruded at 270℃.The refined grain structure was not only due to dynamic recrystallization,but also the synergistic pinning effect of nano-TiCp,precipitated MgZn2 and α-Mn particles.The tensile toughness value of nanocomposite after extrusion improved with increasing the extrusion temperature.Massive micro-cracks formed along the remnant coarse Ca2Mg6Zn3 led to the structural failure during tension.
