Revealing the anisotropy mechanisms of mechanical properties and wear resistance in hot-extruded titanium-silicon brass

Hot extrusion, a process to eliminate casting defects and regulate microstructure, is an industrial commonly used approach for preparing synchronizer rings. In this present study, the titanium-silicon brass tube reinforced by Ti5Si3 short fibers with different orientations were prepared through the hot extrusion. Correspondingly, the effect of Ti5Si3 orientation on the mechanical properties and wear resistance of titanium-silicon brass were investigated and revealed. Results demonstrated that, through hot extrusion, the original randomly distributed Ti5Si3 short fibers are arranged parallel to the extrusion direction with the aspect ratio reducing from 20 to 5. It is also suggested that significant anisotropy is exhibited in tensile strength and wear resistance of the titanium-silicon brasses with different Ti5Si3 short fibers orientations. The yield strength of the sample obtained from the extrusion direction improves by similar to 12 % compared with that of obtained from the transverse direction. In addition, Ti5Si3 short fiber, parallel to the friction surface and parallel to the sliding direction, exhibits the best wear resistance by resisting the plastic deformation of the subsurface layer. However, for Ti5Si3 perpendicular to the friction surface, the matrix of brass would undergo the coordinated deformation deteriorating the wear resistance. Such underlying mechanism for the effect of Ti5Si3 orientation on the strengthening mechanism and wear mechanism was discussed and clarified with incorporation of finite element simulation. It is anticipated that this present study would provide an effective strategy and significant guidance for designing the brass with excellent mechanical properties and wear resistance.