Investigation of Fe–C–Cr and Fe–C–Cr–Ni-based systems with the use of DTA and HT-LSCM methods

Abstract

Three Fe-C-Cr and three Fe-C-Cr-Ni-based alloys containing carbon between 0.318 and 0.410 mass%, chromium and nickel between of 0.001 and 4.990 mass% were studied. Original temperatures of solidus, liquidus and peritectic transformation were determined and clarified for all six specific alloys. Phase transition temperatures were experimentally obtained using differential thermal analysis (DTA), and the start of melting of alloys was investigated using the high-temperature laser scanning confocal microscopy. Additionally, experimental data were compared and discussed with calculation results using SW IDS and Thermo-Calc operating with commercially available thermodynamic database TCFE8. The combination of both experimental methods contributed substantially to investigate more clearly the start of melting. Determination of solidus temperatures/incipient melting point temperatures on DTA curves is often challenging, and there are significant differences when compared with the determination of liquidus and peritectic transformation temperatures. HT-LSCM method brings an improvement in that regard because it can reveal thermal events which are hardly identified on DTA curves. The relation between homogeneity/inhomogeneity of investigated alloys and the initiation of their melting was observed depending mainly on the state of alloys.