The rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

高铁的快速发展要求铜接触线同时具有出色的导电性，热稳定性和机械性能。不幸的是，这些通常是互斥的属性。在这里，我们演示了微观结构的方向优化，并克服了铜线的强度-导电性折衷。我们使用旋转型锻来制备具有纤维质构并沿线轴对齐的超细长晶粒的铜线。该焊丝具有国际退火铜标准（IACS）的97％的高电导率，超过450 MPa的屈服强度，高耐冲击性和耐磨性以及1小时内最高573 K的热稳定性。随后的退火将电导率提高到IACS的103％，同时保持380 MPa以上的屈服强度。