Preparation of ultrafine tungsten powders by in-situ hydrogen reduction of nano-needle violet tungsten oxide

► The ultrafine tungsten powders were prepared. ► Indicating feature of in-situ reduction. ► Empirical relations have been established. ► The nano-needle violet tungsten oxide with morphology instability is key precursor for nano/ultrafine tungsten powders. ► These tungsten powders are the equiaxied particles and have perfect looseness and homogeneity.