Effect of Effect of Cold Isostatic Pressing on the Physical and Mechanical Properties of Tungsten Heavy Alloys

Abstract: The objective of this experimental study is to investigate the effect of cold isostatic pressing (CIP) on the density, mechanical properties and microstructure of 93%W-4.9%Ni-2.1%Fe alloy. Also, to compare between the effect of uni-axial pressing and cold isostatic pressing on the alloy properties.
Elemental powders were mixed using double cone mixer for 2 hours. Cold Isostatic Pressing was applied for consolidation of metal powders into green compacts to obtain cylindrical tensile and impact specimens under different pressures using rubber molds. Finally, the specimens were sintered under vacuum atmosphere at 1470ºC for 90 minutes. The results of density, tensile strength, ductility, hardness and impact resistance obtained from the produced specimens were compared with those obtained using uni-axial compaction. Moreover, the values of the isostatic compaction pressure were varied in order to study their effect on the mechanical properties and to determine the optimum value providing the highest properties. The microstructure analysis indicates that uni-axial compaction can provide a structure with lower contiguity, and a grain size relatively course, while isostatic pressing provides a structure with fine grains and higher contiguity. The obtained results of all measured mechanical properties prepared by cold isostatic pressing showed higher values than those measured on specimens uni-axially compacted, for all values of pressure. We can, also, notice that the relative green density is higher, in case of applying CIP technique, for all values of compaction pressure. It can be concluded that cold isostatic pressing leads to a sensible improvement in alloy properties.