Mechanical Behavior of W-Y2O3 and W-Ti Alloys from 25 A°C to 1000 A°C

The mechanical behavior of pure W, W-0.5 wt pct Y2O3, and W-4 wt pct Ti manufactured by powder metallurgy was studied from ambient temperature to 1000 A degrees C. Y2O3 nanoparticles were added to inhibit grain growth and improve oxidation resistance, while Ti is a sintering activator. Strength and toughness were measured from the three-point bend tests in smooth and notched prismatic bars. The dominant deformation and failure micromechanisms were assessed as a function of temperature for each material through the analysis of the fracture surfaces and transverse cross sections in the scanning electron microscope. In particular, the role played by microstructure, dominant failure mechanisms, and oxidation rates in mechanical behavior were elucidated for each material in the entire temperature range. It was found that Y2O3 improved the high-temperature properties by inhibiting oxidation. The Ti acted as a sintering activator, and the W-Ti alloy was fully dense and presented smaller grain size. Both factors enhanced the mechanical properties at ambient and intermediate temperatures, but the ductile-to-brittle transition temperature (DBTT) of this material was higher, leading to brittle behavior up to very high temperature.