Effect of CPM-9 V powder size on carbide distribution and mechanical properties

Vanadium carbide in CPM (Crucible Powder Metallurgy)-9V powders was characterized based on the powder size to find out how the powder size affected microstructure and mechanical properties of HIP processed products. The acicular and small carbides observed in small powders such as 50 µm and 100 µm indicated that these powders experienced high cooling rate during the gas atomizing process, while large powder showed the round and big carbides as a result of slow cooling rate. With the carbide morphology, the carbide content also affected by the powder size. These differences with the powder size gave an impact on the carbide distribution of the HIP processed products. The 40 meshed sample which had more powders over 300 µm showed both the highest carbide occupancy and average carbide area, suggesting that the final carbide content and size were mainly affected by the large powder. The high volume and large size of the carbide improved mechanical properties. In particular, the large carbide size changed wear mechanism from abrasive wear to adhesive wear.