Role of dendrite branching and growth kinetics in the formation of low angle boundaries in Ni–base superalloys

Newell, M.; Devendra, Kumar; Jennings, Paul; D’Souza, N.

doi:10.1016/j.msea.2005.09.030

Cited by 77 publications

(28 citation statements)

References 9 publications

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“…This can be clearly seen in the DIC data, which shows misorientation accumulating along the length of primary dendrite arms. This is arguably the mechanism underlying the similar misorientation patterns measured by EBSD by Newell et al [7,8]. Furthermore, it has recently been concluded elsewhere that sliver defects are a result of bending moments arising on dendrites from differential thermal contraction between mould and metal [4].…”

Section: Discussionsupporting

confidence: 56%

Origins of misorientation defects in single crystal castings: A time resolved in situ synchrotron X-ray radiography study

Aveson

Reinhart

Nguyen-Thi

et al. 2014

MATEC Web of Conferences

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Abstract. The presence of grain boundaries in single crystal castings is intolerable owing to the detrimental impact on creep and fatigue behaviour. Whilst the origins of many defects such as freckles have been understood since the 1970s, other defects such as slivers, or indeed the small mosaicity observed in many castings have eluded comprehensive treatments. In the present work, in situ X-ray imaging has been used to examine the origin of misorientation defects that arise during solidification. Dendrite deformation was observed, which impacted growth characteristics and led to a permanent misoriention. Digital image correlation analysis showed the dendrites becoming increasingly bent as solidification progressed. In order to probe the deformation modes further, a method was devised to convert standard EBSD data into measurements of bending and torsion angle. It was demonstrated that such defects form as the result of bending moments arising from differential thermal contraction and gravity.

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Section: Discussionsupporting

confidence: 56%

Origins of misorientation defects in single crystal castings: A time resolved in situ synchrotron X-ray radiography study

Aveson

Reinhart

Nguyen-Thi

et al. 2014

MATEC Web of Conferences

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“…The small difference in dendrite growth orientation stems from the geometrical shape of liquid melt pool formed during LSM. Formation of low‐angle grain boundaries is also commonly observed in Ni‐base super alloy cast structures under slow cooling rates …”

Section: Discussionmentioning

confidence: 90%

Laser surface modification of 316L stainless steel

et al. 2017

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Medical grade 316L stainless steel was laser surface melted (LSM) using continuous wave Nd-YAG laser in argon atmosphere at 1 and 5 mm/s. The treated surfaces were characterized using electron backscatter diffraction to study the influence of top surface crystallographic orientation and type of grain boundaries on corrosion resistance, wettability, and biocompatibility. The laser scan velocity was found to have a marginal influence on the surface roughness and the type of grain boundaries. However, the crystal orientation density was found to be relatively high in 1 mm/s samples. The LSM samples showed a higher concentration of {101} and {123} planes parallel to the sample surface as well as a higher fraction of low-angle grain boundaries. The LSM samples were found to exhibit better surface wettability and enhanced the viability and proliferation of human fetal osteoblast cells in vitro when compared to the untreated samples. Further, the corrosion protection efficiency of 316L stainless steel was improved up to 70% by LSM in as-processed condition. The increased concentration of {101} and {123} planes on surfaces of LSM samples increases their surface energy, which is believed to be responsible for the improved in vitro cell proliferation. Further, the increased lattice spacing of these planes and high concentration of low-energy grain boundaries in LSM samples would have contributed to the better in vitro corrosion resistance than untreated 316L stainless steel. Our results indicate that LSM can be a potential treatment option for 316L stainless steel-based biomedical devices to improve biocompatibility and corrosion resistance. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 569-577, 2018.

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“…3. Improvement of creep ductility and thermal fatigue resistance by orientating the preferred <001> crystallographic growth direction, which coincides with the elastically soft direction, parallel to the maximum loading direction (64)(65)(66). In order to grow single-crystal component, a grain selector is implemented into the directional solidification process in a modified Bridgman furnace to ensure that only one grain can survive in the final structure ( Figure 16) (25,26).…”

Section: Grain Selection During Single-crystal Castingmentioning

confidence: 99%