Effect of carbon content on solidification behaviors and morphological characteristics of the constituent phases in Cr-Fe-C alloys

• Published in: Materials characterization Vol. 62; no. 12; pp. 1124 - 1133
• Main Authors: Lin, Chi-Ming, Lai, Hsuan-Han, Kuo, Jui-Chao, Wu, Weite
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-12-2011; Elsevier
• Subjects: BACKSCATTERING; CARBON; CARBON ADDITIONS; CHEMICAL COMPOSITION; CHROMIUM ALLOYS; Chromium base alloys; Concentration (composition); Cr-Fe-C alloys; Cross-disciplinary physics: materials science; rheology; CRYSTAL GROWTH; CRYSTAL STRUCTURE; Electron backscatter diffraction; ELECTRON DIFFRACTION; EUTECTICS; Exact sciences and technology; GRAIN BOUNDARIES; IRON ALLOYS; MATERIALS SCIENCE; MONOCRYSTALS; MORPHOLOGY; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phases; Physics; POLYCRYSTALS; SOLIDIFICATION; Solidification behavior; TEXTURE; TRANSMISSION ELECTRON MICROSCOPY; X-RAY SPECTRA; Crystal growth; Transmission electron microscopy; Electron backscatter diffraction; Cr-Fe-C alloys; Solidification behavior; Electron diffraction; Composition effect; Microstructure; Carbon additions; Solidification
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2011.09.007

A combination of transmission electron microscopy, electron backscatter diffraction and wavelength dispersive spectrum has been used to identify crystal structure, grain boundary characteristic and chemical composition of the constituent phases in Cr-Fe-C alloys with three different carbon concentrations. Depending on the three different carbon concentrations, the solidification structures are found to consist of primary α-phase and [α
+
(Cr,Fe)
23
C
6] eutectic in Cr-18.4Fe-2.3
C alloy; primary (Cr,Fe)
23
C
6 and [α
+
(Cr,Fe)
23
C
6] eutectic in Cr-24.5Fe-3.8
C alloy and primary (Cr,Fe)
7
C
3 and [α
+
(Cr,Fe)
7
C
3] eutectic in Cr-21.1Fe-5.9
C alloy, respectively. The grain boundary analysis is useful to understand growth mechanism of the primary phase. The morphologies of primary (Cr,Fe)
23
C
6 and (Cr,Fe)
7
C
3 carbides are faceted structures with polygonal shapes, different from primary α-phase with dendritic shape. The primary (Cr,Fe)
23
C
6 and (Cr,Fe)
7
C
3 carbides with strong texture exist a single crystal structure and contain a slight low angle boundary, resulting in the polygonal growth mechanism. Nevertheless, the primary α-phase with relative random orientation exhibits a polycrystalline structure and comprises a massive high-angle boundary, caused by the dendritic growth mechanism.
► Microstructures of the as-clad Cr-based alloys are characterized by TEM. ► EBSD technique has been use to characterize the grain boundary of primary phases. ► We examine transitions in morphology about the primary phases. ► Morphologies of primary carbides are polygonal different from primary α-phase. ► Solidification structures rely on C concentrations in Cr-Fe-C alloy.