Synergetic strength-ductility enhancement of ultra-thin W wire by La oxide nanoprecipitates induced pinning effect

Abstract

Ultra-thin W wire is one of the few tools that can cut precious hard materials, including wafers, silicon, and sapphire. Reducing the diameter of tungsten wire by increasing the strength of W wire is the only method to achieve lower material waste and higher precision. Here, we report an ultra-thin La-doped W wire produced by the ice bath assisted non-slip drawing, with a diameter of 38.0 μm and a continuous length exceeding 50 km, exhibiting a tensile strength up to 6.92 GPa with an elongation of 4.2%. Statistical analysis-assisted atomic resolution imaging and element distribution mapping and molecular dynamics (MD) simulations revealed that the hexagonal close-packed (hcp) La oxide precipitates pin at the grain boundaries and form a coherent interface with the body-centered cubic (bcc) W matrix, inducing the nano twins and local hcp region in bcc W matrix, which originates lattice distortion and dislocations, and altered the plastic deformation mechanism of W. The coherent W-La oxide interface enhances the plastic deformation of grain boundaries and effectively elevates the uniform deformation, thereby simultaneously enhancing the strength and ductility. The ice bath assisted non-slip drawing is applicable to diverse metal wires and is of high potential for scalable and industrial applications.