Deformation and Fracture of Ti-6Al-4V/TiC Composites 3D Printed using Wire-Feed Electron Beam Additive Manufacturing under Uniaxial Tensile Stress

The deformation and fracture patterns of Ti–6Al–4V/TiC composites 3D printed by wire-feed electron beam additive manufacturing using Ti–6Al–4V wire pre-electrospark alloyed with carbide-containing electrodes or by simultaneous melting of titanium wire and TiC powder are investigated. It is shown that Ti–6Al–4V/TiC composites obtained by both methods are characterized by the same microstructure and volume fraction of the carbide phase (~2%) but different sizes of TiC inclusions. It is found that the ductility of the Ti–6Al–4V/TiC composite obtained by electrospark alloying of the wire and containing TiC inclusions with a diameter of ~1 μm is significantly higher than that of the specimen 3D printed by simultaneous melting of titanium wire and TiC powder, in which the inclusion sizes vary within 15–30 μm. Different fracture characteristics of the investigated Ti–6Al–4V/TiC composites under uniaxial tensile stress were revealed. Three-dimensional modeling of elastic-plastic deformation and fracture of model Ti/TiC composites under mechanical loading is carried out using the method of movable cellular automata. The influence of the size and hardness of TiC particles, as well as the character of their distribution in the titanium matrix, on the regularities of crack initiation and propagation in the model composite is demonstrated. It is shown that the inhomogeneous distribution of large carbide inclusions in the titanium matrix is a key factor for crack initiation and propagation in the model composites.