In the last years alloying elements like Ni, Cu and Mo have been more and more replaced by cheaper alloying elements like Cr and Mn [1, 2]. These latter elements provide good hardenability and low costs at the same time which makes them attractive elements for sinter hardening alloys. Chromium (as well as manganese) is however sensitive to oxidation, and therefore sintering of alloys containing Cr is a difficult task. The problem is that Cr forms stable oxides which weaken the sintering contacts if they are not reduced properly. Reducing these oxides is only possible at high sintering temperatures, with the presence of C as a reducing agent. This has been the task of numerous studies [3, 4, 5]. Beside this, Cr has a strong tendency to form nitrides [6]. The nitrides appearing in the phase diagram Cr-N are Cr_2N and CrN.
展开▼
