Influence of ECAP deformation routes on grain refinement, mechanical properties and texture of zinc

Zinc (Zn) has potential for applications such as bioresorbable implants but is held back by poor mechanical properties. Equal channel angular pressing (ECAP) enhances mechanical properties by refining the microstructures and can alter crystallographic texture and deformation mechanisms. Here, ECAP of Zn using four standard deformation routes (RA, RB A , RB C and RC - refer to Figure 1 for pressing sequences) was investigated to assess impacts on the microstructure and mechanical properties. Four passes of ECAP reduced the average grain sizes by >50 % and increased yield strengths by up to 80 % compared to the starting material. Varying the deformation route altered the material strain path which impacted microstructure refinement, including uniformity and crystallographic textures. Route A resulted in larger average grain size compared to other routes and there was significant variation of the grain size and hardness across the billet section. Route B C gave most consistent grain refinement and strengthening, while route C had the best processability as it allowed consistent preparation of crack-free billets with a smooth finish. Contrastingly, route B A resulted in heavily cracked billets, while route A led to cracking at the tail of billets. Characteristic crystallographic textures were induced by each route with B A , B C and C exhibiting dominant Y fibre textures, which is associated with ideal shear, oriented according to the material strain path. Meanwhile, less common dominant B fibre texture was formed in billets pressed by route A. The study provides insights to enhance mechanical properties of Zn by ECAP and to influence crystallographic textures which may affect corrosion and biodegradation behaviours.