Effects of powder mixing technique and tungsten powder size on the properties of tungsten heavy alloys

Properties of tungsten heavy alloys are known to vary with process parameters such as sintering temperature, time and atmosphere. In this study, tensile properties of the 92.5W-5.25Ni-2.25Fe and 90W-7Ni-3Fe heavy alloys were found to be influenced by powder mixing technique and tungsten powder size. For a given tungsten powder grade (mean particle size 10.5 or 3.4 mu m), attritor milled alloys exhibited better tensile properties than those of the turbula-mixed alloys. Compared to finer grade, coarser tungsten powder generally resulted in alloys with higher ductility when turbula mixer was used. Overall, the alloys prepared from turbula mixed powders containing finer tungsten grade showed the lowest tensile properties. Metallographic analyses revealed that these alloys failed in more brittle fashion as a result of a high degree of contiguity of tungsten grains, which was inherited from powder mixing step. (C) 2000 Elsevier Science S.A. All rights reserved.