Abstract
Experiments in the sintering of tungsten activated with different amounts of nickel and iron have been carried out. Almost complete densification has been obtained through sintering in a hydrogen atmosphere in the range of 1100–1500°C. The grain size coarsening of the sintered bodies is very poor because of the low temperatures involved; grain growth starts at a temperature of 1400–1500°C and nickel additions enhance growth more than iron. An explanation of the nickel and iron activating effect is given both through oriented vacancy flow generated by the Frankel-Kirkendall effect, originated by the widely different iron and nickel-tungsten diffusion coefficients, and through annihilation of the tungsten dislocations by dissolution in the activating agent. A justification of nickel as the best activating agent is given in terms of poor nickel solubility in the tungsten.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
