Influence of high energy ball milling on density and microstructure of fine-grained W-Y_2O_3 alloy

The ultrafine/nano composite powder of W with addition of trace Y2O3 was prepared by sol-spray drying-hydrogen thermal multi-step reduction. After cold pressing forming and sintering at high temperature(1 800~ 1950 ℃), the trace yttrium oxide dispersion of fine-grained tungsten alloy was fabricated. The influence of the high energy ball milling on the powder morphology, alloy density and microstructures was tested and discussed. The effects of ball milling and sintering temperature on densification and microstructure of the sintered alloy were discussed. The results show that: the Fsss particle size is below 0.9 μm, the ultrafine/nano composite powder of W-Y2O3 has high sintering activity so that all materials have high relative density above 97.4% after sintering at 1 860 ℃. The high-energy ball milling after reduction of W-Y2O3 compound powder can significantly improve the level of densification, which can be up to 99.4% when sintered at 1 860 ℃; the grain of W-Y2O3 composite powder sintered at 1 860 ℃ without high energy ball milling is very small, which is only about 3 μm, but the distribution is not uniform. Appropriate energy ball milling is beneficial to improving the uniformity of the microstructure, while it can make the grain bigger.