Rapidly solidified MC carbide morphologies of a laser-glazed single-crystal nickel-base superalloy

Solidification path of single-crystal nickel-base superalloys with minor carbon additions under laser rapid directional solidification conditions

“…The DSC profiles show that there is a reaction peak at~1612 K just below the liquidus (~1635 K), which was identified as a γ-MC eutectic peak in earlier research [3][4][5][6] and verifies these phases formed after the growth of γ dendrites to be MC carbides. Similar to earlier research [21,22], the EDS analysis shows that these carbides are mainly Ti-and Ta-rich. In comparison, owing to a great increase in cooling rate, the primary dendrites are finer and the carbides distributed in the interdendritic regions of sample B become non-branching, small rods (or layers) (see Fig.…”

“…This eutectic-type solidification reaction can explain the formation of MC carbides with a branching morphology. Similar eutectic-type solidification reaction of MC carbides was also observed under higher cooling rates (~6.2 × 10 4 and 1.4 × 10 5 K/s) in earlier research on a superalloy with a lower C content (b0.01%) by Wang et al [21], reconfirming that with a relatively high C content (0.015%) this reaction is indeed after the epitaxial directional growth of single-phase γ dendrites. Such γ-MC eutectic reactions have also been widely reported in the superalloys with higher C contents based on the analyses of DSC curves [3][4][5][6] or their morphology, location, and compositions [22][23][24].…”

“…With this in mind, of particular interest is the effect of minor carbon additions on the solidification sequence of SX superalloys under laser rapid directional solidification (LRDS) conditions. Unfortunately, although many researchers have focused on the morphology and growth mechanism of MC carbides [21,22] and on the solidification behaviors of early DS superalloys with relatively high carbon contents [23,24], the solidification path of the SX superalloys with minor carbon additions has not yet been reported under LRDS conditions. Consequently, the main objective of this study is to reveal the solidification sequence of the SX nickel-base superalloys with minor carbon additions under RS conditions.…”

Characterization of laser‐treated Rene 41 surface due to B4C and SiC particles at surface prior to laser treatment

“…This is attributed to the interdendritic zones where solidification takes place slowly and liquid phase solidifies lastly. This, in turn, results in solute enrichment leading to the formation of MC carbides . The secondary dendrite arms are present because of large dendrites formed below the dense layer, which are attributed to relatively slow cooling rates as compared to that of at the surface.…”

Eutectic MC carbide growth morphologies of a laser clad TiC/FeAl composite coating

“…Previously, considerable research has been carried out on TiC type MC carbide in different solidification conditions and different alloy system. The near-equilibrium growth morphology of MC carbide in nickel-base superalloys are octahedral blocks and these would transform gradually to Chinese-script morphology, flower-like and radially branched colonies with increasing cooling rate [9][10][11][12]. Meanwhile, the growth morphologies of MC carbide of a laser surface alloyed g-TiAl alloy with carbon is found to have a faceted dendritic morphology having zig-zag platelet or three-dimensional faceted-platelet networks on the growth surface of dendritic arms [13], cross-petal-like with symmetrical arms and irregular block or undeveloped dendrite [14].…”