The influence of Tip aspect ratio on the microstructure, mechanical properties, and work hardening behavior of the Tip/Mg-Gd-Y-Zn composites.

In this work, the spherical Ti p was introduced into Mg-7Gd-2Y–3Zn (GWZ723) alloy by semi-solid stir casting process, then the Ti p /GWZ723 composites were prepared and subjected to extrusion at 380–450 °C. After that, the aspect ratio of the Ti p was adjusted according to the extrusion temperature. The effects of the Ti p aspect ratio on microstructure, mechanical properties, and work-hardening behavior of Ti p /GWZ723 composites were investigated. The results revealed that after hot extrusion, the Ti p elongated along the extrusion direction (ED), and its aspect ratio increased as the decrease of extrusion temperature. When the extrusion temperature decreased to 380 °C, the aspect ratio of the Ti p reached to 12:1. With the increasing Ti p aspect ratio, the hardness of the Ti p decreased while the Mg matrix increased. Moreover, both the recrystallized grains and LPSO phase were also refined simultaneously. The yield strength (YS), ultimate tensile strength (UTS), work hardening rate and dynamic recovery rate of the Ti p /GWZ723 composites increased with the increasing of Ti p aspect ratio. During the tensile process, strain concentration tended to occur at the sharp corner of the elongated Ti p , nevertheless, the strain distribution in the matrix became more uniform accompanied with the increasing Ti p aspect ratio, which was conducive to suppress crack initiation and delay fracture. It was the laminar-like configuration formed by the elongated Ti p and the Mg matrix along the ED contributed to the excellent comprehensive mechanical properties of the Ti p /GWZ723 composites. When the Ti p aspect ratio was 12:1, the YS and UTS reached as high as 454.3 MPa and 492.2 MPa, respectively. [Display omitted] • The aspect ratio of the Ti p elongates from 1:1 to 12:1 after extrusion. • The elongated Ti p weakens its hardness but strengthens the Mg matrix. • The elongated Ti p makes the strain distribution more uniform. • Laminar-like Ti p /GWZ723 composites exhibits YS of 454.3 MPa and UTS of 492.2 MPa. [ABSTRACT FROM AUTHOR]