Improving the ductility and toughness of nano-TiC/AZ61 composite by optimizing bimodal grain microstructure via extrusion speed  

作　　者：Lingling Fan Mingyang Zhou Wulve Lao Yuwenxi Zhang Hajo Dieringa Ying Zeng Yuanding Huang Gaofeng Quan 

机构地区：[1]Key Laboratory of Advanced Technologies of Materials,Ministry of Education,Chengdu 610031,China [2]School of Materials Science and Engineering,Southwest Jiaotong University,Chengdu 610031,China [3]Institute of Material and Process Design,Helmholtz-Zentrum Hereon,Geesthacht 21502,Germany [4]Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China [5]School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China [6]Institute of Metallic Biomaterials,Helmholtz-Zentrum Hereon,Geesthacht 21502,Germany

出　　处：《Journal of Magnesium and Alloys》2024年第8期3264-3280,共17页镁合金学报（英文）

基　　金：support from China Scholarship Council(No.202107000038);the Na-tional Natural Science Foundation of China(52004227).

摘　　要：In this study,the nano-TiC/AZ61 composites with different heterogeneous bimodal grain(HBG)structures and uniform structure are obtained by regulating the extrusion speed.The effect of HBG structure on the mechanical properties of the composites is investigated.The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed.When the extrusion speed increases from 0.75 mm/s to 2.5 mm/s or 3.5 mm/s,the microstructure transforms from uniform to HBG structure.Compared with Uniform-0.75 mm/s composite,Heterogeneous-3.5 mm/s composite achieves a 116.7%increase in ductility in the plastic deformation stage and almost no reduction in ultimate tensile strength.This is mainly because the lower plastic deformation inhomogeneity and higher strain hardening due to hetero-deformation induced(HDI)hardening.Moreover,Heterogeneous-3.5 mm/s composite achieves a 108.3%increase in toughness compared with the Uniform-0.75 mm/s composite.It is mainly because coarse grain(CG)bands can capture and blunt cracks,thereby increasing the energy dissipation for crack propagation and improving toughness.In addition,the CG band of the Heterogeneous-3.5 mm/s composite with larger grain size and lower dislocation density is more conducive to obtaining higher strain hardening and superior blunting crack capability.Thus,the increased ductility and toughness of the Heterogeneous-3.5 mm/s composite is more significant than that Heterogeneous-2.5 mm/s composite.

关 键 词：Nano-TiC/AZ61 composite Extrusion speed Heterogeneous bimodal grain structure Increasing ductility mechanism Toughening mechanism 

分 类 号：TB33[一般工业技术—材料科学与工程]