Microstructure and mechanical properties of TiC nanoparticle-reinforced Mg−Zn−Ca matrix nanocomposites processed by combining multidirectional forging and extrusion  

联合多向锻造与挤压变形TiC纳米颗粒增强Mg−Zn−Ca基复合材料的组织与力学性能

作　　者：Kai-bo NIE Zhi-hao ZHU Paul MUNROE Kun-kun DENG Ya-chao GUO 聂凯波;朱智浩;Paul MUNROE;邓坤坤;郭亚超(太原理工大学材料科学与工程学院,太原030024;School of Materials Science and Engineering,University of New South Wales,Sydney,NSW 2052,Australia)

机构地区：[1]College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,China [2]School of Materials Science and Engineering,University of New South Wales,Sydney,NSW 2052,Australia

出　　处：《Transactions of Nonferrous Metals Society of China》2020年第9期2394-2412,共19页中国有色金属学报（英文版）

基　　金：Projects(51771129,51401144,51771128)supported by the National Natural Science Foundation of China,Project supported by the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi,China;Projects(2015021067,201601D011034)supported by the Natural Science Foundation of Shanxi Province,China;Project(201703D421039)supported by the International Cooperation in Shanxi,China;Project supported by the China Scholarship Council。

摘　　要：TiC nanoparticle-reinforced Mg−4Zn−0.5Ca matrix nanocomposites were processed by combining multidirectional forging(MDF)and extrusion(EX).The grain size of the nanocomposite after MDF+EX multi-step deformation was significantly decreased compared with that processed only by MDF.The average size of the recrystallized grains gradually increased after EX with increasing the number of MDF passes at 270℃.However,the grain size significantly decreased by MDF processing at 310℃.Both fine and coarse MgZn2 phases appeared in the(MDF+EX)-processed nanocomposites,and their volume fractions gradually increased with increasing the number of MDF passes before EX.Ultrahigh tensile properties(yield strength of^404 MPa,ultimate tensile strength of^450.3 MPa and elongation of^5.2%)were obtained in the nanocomposite after three MDF passes at 310℃ followed by EX.This was attributed to the refinement of the recrystallized grains,together with the improved Orowan strengthening provided by the precipitated MgZn2 particles that were generated by MDF+EX multi-step deformation.采用多向锻造(MDF)和挤压(EX)相结合工艺对TiC纳米颗粒增强Mg−4Zn−0.5Ca基纳米复合材料进行变形。与仅单一MDF相比,经MDF+EX变形后纳米复合材料的晶粒尺寸显著减小。当MDF温度为270℃时,随MDF道次的增加,经EX变形后再结晶(DRX)晶粒的平均尺寸逐渐增大;而当MDF温度为310℃时,经EX变形后DRX晶粒的平均尺寸显著减小。经MDF+EX多步变形后纳米复合材料中同时出现细小和粗大的MgZn2相,这些MgZn2相的体积分数随EX前MDF道次的增加而逐渐增大。对温度为310℃经3道次MDF后的纳米复合材料进行EX,其屈服强度、极限抗拉强度和伸长率分别达到~404 MPa,~450.3 MPa和~5.2%。这主要与MDF+EX多步变形后晶粒细化强化及MgZn2析出相引起的Orowan强化有关。

关 键 词：magnesium matrix nanocomposite multi-step deformation multidirectional forging mechanical properties MgZn2 phases 

分 类 号：TB333[一般工业技术—材料科学与工程]