The effect of porosity on distortion of liquid phase sintered tungsten heavy alloys

Porosity effects on distortion during liquid phase sintering were investigated experimentally. W-Ni-Fe alloys with compositions ranging from 78 to 93 wt% tungsten were liquid phase sintered at 1500°C for 30 min. Surprisingly, the results show that porosity has no appreciable effect on distortion. After sintering, similar distortion profiles were obtained for compacts with both high and low green porosities. On the other hand, distortion reduced with increasing solid:liquid ratio. No distortion occurred for samples with 93 wt% tungsten. Quenching experiments showed the onset of slumping was delayed until densification neared completion. In high liquid content samples, this means slumping occurred within a few minutes after melt formation, corresponding to liquid exudation. The results are in agreement with model predictions by German. The sintered microstructures were quantitatively measured for solid volume fraction and contiguity. No apparent effects of green porosity on micro structural evolution were observed. © 1999 Published by Elsevier Science Ltd. All rights reserved.