Improving the mechanical properties and thermal shock resistance of W-Y2O3 composites by two-step high-energy-rate forging

Yttria dispersion-strengthened tungsten composites with enhanced thermal and mechanical properties were fabricated by powder metallurgical methods in this work. The processing route involves the doping of yttria particles in the tungsten powders by liquid-liquid doping process, followed by hot pressing and two-step high-energy-rate forging (HERF). The microstructure, thermal conductivity, mechanical properties and thermal shock resistance of the hot-pressed W-Y ₂O ₃ composites and the HERF processed W-Y ₂O ₃ composites were comparatively investigated. The bending strengths of the HERF processed W-Y ₂O ₃ composites increased significantly compared with that of the hot-pressed W-Y ₂O ₃ billets. The HERF W-Y ₂O ₃ material presented a ductile behavior even at room temperature with a maximum flexural strain of 4.4% and a yield stress of 2324.5 MPa. At 100°C, the material also exhibits evident plasticity with a flexural strain of 5.9% and the yield stress is up to 1931.9 MPa. The thermal conductivity of the W-Y ₂O ₃ composite is 170 W/mK, which is close to the deformed pure W. The thermal shock response of the HERF processed W-Y ₂O ₃ is also evaluated by applying edge-localized mode like high heat loads (100 pulses) with an energy density of 0.16–1 GWm ⁻² at various temperatures in an electron beam facility. The thermal shock results indicate that the cracking threshold of the HERF processed W-Y ₂O ₃ at RT is between 0.55 GWm ⁻² and 0.66 GWm ⁻². The cracking threshold of the HERF W-Y ₂O ₃ at 100°C and above is higher than 1 GWm ⁻².