Microstructure and mechanical properties of intragranular W-Cu/TiC-ZrC composite prepared by reactive melt infiltration at 1300 °C

Abstract Newly intragranular W-Cu/TiC-ZrC composites with nano W dispersoids in TiC matrix have been prepared by reactive melt infiltration at 1300 °C for 1 h in vacuum using molten Zr-Cu binary alloys and a (Ti 0.75 ,W 0.25 )C solid solution powder as raw materials. The as-synthesized composites consist of major phases of W, Cu, TiC and ZrC. With the decrease of Zr content from 66 to 21 at.% in the Zr-Cu infiltrator, the reaction formed W phase in the composite has changed from micron-sized intergranular grains to nano-sized rounded inclusions in TiC y grains. The crystallographic orientation relationship at W and TiC interfaces are detected as: 0 1 1 ¯ W / / 1 1 1 ¯ TiC & 0 1 1 W / / 0 1 1 TiC and 4 1 1 W / / 4 2 4 TiC & 0 1 1 ¯ W / / 4 2 ¯ 3 ¯ TiC . Nano-sized lamellar structure with both W and Cu rich is detected to have super-lattice structure based on the TiC lattice. The elastic modulus, flexural strength, fracture toughness of the intragranular W-Cu/TiC-ZrC composite infiltrated with Zr 14 Cu 51 melt are 207.5 GPa, 457 MPa and 10.21 MPa∙m 1/2 , respectively. The intragranular nano W dispersoids and ribbon like precipitates hinder crack propagation via crack deflection and bridging.