Crack suppression and ductility modification of additive manufactured Ti6Al4V/W heterostructure interface via Nano-TiC reinforcement

Abstract

The incorporation of titanium alloy Ti-6Al-4 V (TC4) and tungsten (W) into hybrid structures presents considerable potential for utilization in extreme environments. However, challenges such as interfacial brittleness, residual stresses, and limited metallurgical compatibility impede effective bonding. In this study, laser powder bed fusion (L-PBF) was employed to fabricate TC4/W bimetallic heterostructures, with nano-TiC particles introduced at the interface to improve interfacial bonding and mechanical performance. Experimental findings indicate that the addition of nano-TiC effectively reduces interfacial defects, refines grain structure by decreasing the average grain size by 16.7–27.5 %, and facilitates the formation of β-Ti/W infinite solid solutions with fully coherent interfaces. These microstructural enhancements lead to significant improvements in mechanical properties, as evidenced by an increase in ultimate tensile strength (UTS) from 600 MPa to 725 MPa and an improvement in elongation (EL) from 6.8 % to 10.3 %. The observed strengthening mechanisms primarily result from grain boundary refinement, dislocation pinning, and Orowan strengthening effects. The findings of this study present a feasible approach for optimizing additive-manufactured TC4/W composites to meet the stringent demands of aerospace and nuclear applications.