Hot Isostatic Pressing of Tungsten-Nickel-Iron Composites (Hetisostatisk Pressning av Volfram-Nickel-Jaern-Kompositer)

摘要

Heavy metals or tungsten-nickel-iron alloys are usually produced from powders by liquid phase sintering. During this process a nickel-iron-tungsten melt is formed in which tungsten crystals are growing to a spherical shape. The resulting particle composite structure gives the material good mechanical properties. Studies have been made to learn to what extent the liquid phase sintering could be replaced by HIP. For this purpose blends of different W, Ni and Fe powders were filled into steel containers, reduced by hydrogen around 800 deg C, evacuated and sealed. The investigation shows that the microstructure after HIP is dependent of the powder grain size. To be able to improve the microstructure after HIP the grain size of nickel and iron powders must be about one tenth of that of the tungsten powder.