Sintering Microstructure and Properties of Trace Yttrium Dispersion Strengthened Fine-Grained W Alloys

Through the ordinary moulding-presintering and sintering at 1800-1950 degrees C, fine-grained tungsten alloys were fabricated with ultrafine/nano composite powders of W-0.3%Y which were prepared by sol-spray drying-nano in situ composite. The microhardness and tensile strength of alloys were detected. Moreover, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to examine microstructure and fracture morphology. The evolution of sintering and fracture behavior was investigated. The results show that the added trace yttrium exists in the form of Y2O3 as the second phase particles dispersing throughout grain boundary and the inner of W grains, restraining tungsten grain growth and refined the grains significantly, which improves the mechanical properties of the alloys. Besides, the fracture mode of tungsten alloy with adding trace yttrium changes from intergranular fracture of pure tungsten to mainly intergranular fracture and part transgranular fracture.