THE EFFECT OF COBALT ADDITIVE ON MICROSTRUCTURE AND PROPERTIES OF W-CU COMPOSITES PREPARED BY SINTERING AND INFILTRATION PROCESSES

In the present paper, the influence of cobalt additive on the sintering/infiltration behavior of W-Cu composite was studied. For this purpose, the mixed powders of tungsten and cobalt were compacted by CIP method and then sintered at ۱۴۵۰, ۱۵۵۰ and ۱۶۰۰ °C in a hydrogen atmosphere. The sintered specimens at ۱۵۵۰ °C were subsequently infiltrated with liquid copper at ۱۲۵۰ °C for ۱۰, ۶۰ and ۱۲۰ min. The microstructure and composition of samples were evaluated using SEM, EDS as well as XRD techniques. The density of the sintered samples was measured by Archimedes method. Vickers indentation test was used to measurement hardness. It was found that sintering mechanism of tungsten powder depends on temperature and cobalt additive content. Also, the best infiltration behavior was observed in the samples with optimum cobalt value. In addition, it was found that the W-W contiguity as well as dihedral angle decreases as cobalt increases. Density and hardness of infiltrated specimens are attained ۱۶.۲۸-۱۶.۷۹ g.cm-۳ and ۲۲۰-۲۵۱ VHN, respectively.