Enhanced tensile ductility of tungsten microwires via high-density dislocations and reduced grain boundaries

Abstract

• W microwires with designed microstructure were microfabricated under EBSD guidance. • High-density dislocations were introduced in W with reduced grain boundaries. • Ultrahigh strength and ductility were achieved in engineered W microwires. • The motion of pre-existing high-density dislocations produces high ductility of W. Despite being strong with many outstanding physical properties, tungsten is inherently brittle at room temperature, restricting its structural and functional applications at small scales. Here, a facile strategy has been adopted, to introduce high-density dislocations while reducing grain boundaries, through electron backscatter diffraction (EBSD)-guided microfabrication of cold-drawn bulk tungsten wires. The designed tungsten microwire attains an ultralarge uniform tensile elongation of ~10.6%, while retains a high yield strength of ~2.4 GPa. in situ TEM tensile testing reveals that the large uniform elongation of tungsten microwires originates from the motion of pre-existing high-density dislocations, while the subsequent ductile fracture is attributed to crack-tip plasticity and the inhibition of grain boundary cracking. This work demonstrates the application potential of tungsten microcomponents with superior ductility and workability for micro/nanoscale mechanical, electronic, and energy systems.