Mg-Gd-Zn高稀土镁基复合材料的变形行为

Deformation behaviors of Mg-Gd-Zn based high rare-earth magnesium matrix composites

通过半固态搅拌铸造和热挤压工艺制备了TC4(Ti-6Al-4V)颗粒增强Mg-13Gd-5Y-2Zn-1Mn镁基复合材料,采用光学显微镜、扫描电镜、单轴压缩试验和三点弯曲试验分析了其显微组织及变形行为。结果表明,在挤压过程中,TC4颗粒阻碍了其周边晶粒的动态再结晶过程和长周期堆垛有序(LPSO)相的变形,晶粒的织构方向发生改变,在基体内形成了LPSO相、TC4颗粒、再结晶晶粒和变形晶粒组成的不同区域。复合材料的压缩性能相较于基体材料得到了较大提升,其压缩屈服强度和极限抗压强度可达到450和637 MPa,压缩应变为10.1%。在压应力作用下,复合材料内出现以<1120>86°孪晶为主的大量变形孪晶,产生了较强的孪晶强化。

TC4(Ti-6Al-4V) particle reinforced Mg-13Gd-5Y-2Zn-1Mn magnesium matrix composites were prepared by semi-solid stirring casting and hot extrusion processes,and their microstructure and deformation behavior were analyzed using optical microscope,scanning electron microscopy,uniaxial compression testing and three-point bending testing.The results show that during the extrusion,the TC4 particles hinder the dynamic recrystallization process of its surrounding grains and the deformation of long-period stacking ordered(LPSO) phases,the texture direction of the grains is changed,and different regions composed of LPSO phase,TC4 particles,recrystallized grains and deformed grains are formed in the matrix.The compressive performance of the composites has been significantly improved compared to the matrix,with compressive yield strength and ultimate compressive strength reaching 450 and 637 MPa,and compressive strain of 10.1%.Under compressive stress,a large number of deformation twins,mainly <1120>86° twins,appear in the composites,resulting in strong twinning strengthening.