Effect of ZrO2 content on microstructure and mechanical properties of W alloys fabricated by spark plasma sintering

The ultra-fine-grained ZrO2-reinforeced W composites were obtained by hydrothermal synthesis method and spark plasma sintering. The precursors of WO3 and Zr(OH)(2) were evenly mixed in aqueous solutions via the liquid-liquid doping, a hydrothermal method. The addition of ZrO2 could significantly refine W particles, and thus the ultra-fine and well-mixed W-ZrO2 composite powders were obtained after reduction, with the average size of 2 mu m for W particles and similar to 20 nm for Y2O3 -stabilized ZrO2 particles. The relative density of the sintered samples increases from 92.8% to 98.9% with increasing ZrO2 content. The W-1.5wt%ZrO2 alloy possesses the prominent properties of 538.8 HV for microhardness, and 1628 MPa for compressive strength when compressed to 21% strain-to-failure at room temperature and a strain rate of 1.7 x 10(-3)s(-1). The high temperature compressive tests shows that the existence of peak stress is not observed in the true stress-stain curves, indicating that the dynamic recovery is the main cause of deformation softening during deformation.