M7C3 and M3C carbides in Fe-1C-4.4Cr-l.6V alloy


Figure 1: Scanning electron micrograph of an Fe-1C-4.4Cr-l.6V alloy cooled from the liquid at 5 C/mn. The contrast has been enhanced, enabling two carbides to be distinguished in the eutectic constituent, M7C3 (dark) and M3C (lighter). The matrix is austenite that has transformed to fine pearlite. The approximate compositions of the carbides are: M7C3 = (Fe3.5Cr2.5V1)C3, M3C = (Fe1.5Cr1V0.5)C. Courtesy INPG, Grenoble. Scale bar: 10 µm.

Carbide name: M7C3, M3C
Record No.: 1182
Carbide formula: M7C3, M3C
Carbide type: M7C3, M3C
Carbide composition in weight %: M7C3, M3C
Image type: SEM
Steel name: Fe-1C-4.4Cr-l.6V alloy
Mat.No. (Wr.Nr.) designation: No data
DIN designation: No data
AISI/SAE/ASTM designation: No data
Other designation: No data
Steel group: Chromium-vanadium steels
Steel composition in weight %: Fe-1C-4.4Cr-l.6V
Heat treatment/condition: No data
Note: Unusual morphologies: Another example is shown in Figure 1, where agglomerates can be seen in the interdendritic regions of an as-solidified Fe-C-Cr-V alloy. In these materials, the addition of small amounts of vanadium or niobium changes the pseudo-peritectic reaction gamma + M7C3>M3C in the Fe-Cr-C system to a eutectic reaction gamma >M3C + M7C3 + gamma. M7C3 and M3C carbides are effectively identified, but with an interwoven configuration, not very typical of a ternary eutectic morphology. It is not possible to conclude from the microstructure whether it is the result of a eutectic or peritectic reaction. Reasoning must be based on tie-lines determined at several temperatures.
Links: No data
Reference: Not shown in this demo version.

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