Abstract
Mechanical alloying was carried out using pure iron, pure niobium and graphite powders. The very fine homogeneous alloy powder was obtained after the mechanical alloying for 144.0 ks. The very fine NbC particles were precipitated in this alloy powder by the heat-treatment in the temperature range of 873-1273 K. The mean particle size of the NbC was decreased with decreasing the heat-treatment temperature, resulting in about 8.5 nm by the heat-treatment at 873 K for 3.6 ks. The mean particle size of the NbC precipitated by the present method was finer than that of the NbC powder using as starting materials crushed and dispersed by mechanical alloying. The micro-Vickers hardness values were very high in the lower temperature range, however they were decreased with increasing the heat-treatment temperature.
