Cu redistribution during sintering of Fe–2Cu and Fe–2Cu–0·5C compacts

Abstract

The effective use of alloying elements in powder metallurgical steels requires a deep understanding of their redistribution kinetics during sintering. In this work, interrupted sintering trials of Fe–2Cu and Fe–2Cu–0·5C compacts were performed. Moreover, diffusion simulations of Cu in γ-Fe using Dictra were performed. It is found that transient liquid phase penetrates the Fe interparticle and grain boundaries in less than 3 min of holding time. However, C addition limits the penetration of liquid Cu, particularly into grain boundaries of large Fe particles. The results also show that the mean diffusion distance of Cu in γ-Fe in the C added system is slightly lower than that in the C-free system at 3 min of holding time; however, after 33 min, the mean diffusion distance is similar in both systems. The diffusion distances of Cu in γ-Fe, predicted by Dictra, are in good agreement with the measured values.

Keywords:

• Cu redistribution kinetics
• Diffusion
• Wetting
• Microstructure
• Dilatometry
• SEM/EDXS
• Dictra
• Powder metallurgical steels

Acknowledgements

This work was performed within the VINN Excellence Center Hero-m, financed by VINNOVA, the Swedish Governmental Agency for Innovation Systems, Swedish industry, and KTH Royal Institute of Technology. The authors are grateful to Hans Söderberg (formerly at Swerea KIMAB and now at Sandvik AB) for performing the sintering trials, Joakim Odqvist (KTH) for support in Dictra simulations, and Grosser Heike (Höganäs AB) for assistance in microstructure analysis.