| 1 | Effect of extrusion temperature on microstructure and mechanical properties of a low-alloying and ultra-high strength Mg-Zn-Ca-Mn matrix composite containing trace TiC nanoparticles显示文摘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. | K.B.Nie Z.H.Zhu K.K.Deng J.G.Han | 2020 | Journal of Magnesium and Alloys2020，8，3： | 4 |
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