Microstructure and mechanical properties of nano-WC/TA2 composites fabricated by directed energy deposition

Abstract

TA2 titanium alloys are widely used in aerospace, chemical, and medical devices with low density, high strength, high corrosion resistance, and good machinability. However, the mechanical properties of TA2 reduce the components' service life and application prospects. In this paper, WC/TA2 composities were prepared using laser direct energy deposition (DED) method to study the changes in microstructure and mechanical properties with the different nano WC additions. The results show that with the increase of nano WC, the in-situ generated TiC shows different morphologies, the hardness and wear resistance are firstly enhanced and then reduced, the wear mechanism changes from adhesive wear to abrasive wear, and the fracture mode changes from ductile fracture to brittle fracture. Overall, the composite with the 14 wt% WC addition exhibits the best performance, the microhardness and the wear rate are 135.4 % and 75.2 %, respectively, compared with the pure TA2 deposited layer. The tensile strength in the parallel direction increased by 162.7 %, and the tensile strength in the vertical direction increased by 132.6 %.