Analysis of Microstructure in Surface-melted Region of Ni-base Single Crystal Superalloy

This work investigated microstructure in the surface-melted region of Ni-base single crystal superalloy CMSX-4 by using a diode laser beam as a heating source. Such processing parameters as laser power and scanning speed in laser surface melting were varied while defocusing distance and shielding gas (Ar) flow rates were fixed. Specimen surfaces were arranged parallel to the (001) of base alloy. The microstructure in the melted region was analyzed by optical microscopy and SEM. Crystal orientation of the melted region was analyzed using electron backscattered pattern analysis. The microstructure was remarkably changed when the heat input of surface melting was varied. The surface-melted region was found to solidify into a single crystal with directional dendrites that grew along the [001] directions under low heat input conditions. The surface-melted region was also a single crystal with disoriented dendrites that grew along the [100] or [010] directions under medium heat input conditions. In contrast, the melted region consisted of poly crystals with stray crystals under high heat input conditions. Such tendencies were also observed in the melted region with gas tungsten arc. These results demonstrate that the surface-melted region can solidify into a single crystal under conditions in which larger temperature gradient and higher solidification rates can be achieved.

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Crystal Plasticity Assessment to Crystallographic Stage I Cracking in a Ni-Based Single Crystal Superalloy

SSRN Electronic Journal ◽

10.2139/ssrn.3275453 ◽

2018 ◽

Author(s):

Motoki Sakaguchi ◽

Ryota Komamura ◽

Mana Higaki ◽

Xiaosheng Chen ◽

Hirotsugu Inoue

Keyword(s):

Single Crystal ◽

Crystal Plasticity ◽

Stage I ◽

Single Crystal Superalloy

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Abnormal Increase of TCP Phase During Heat Treatment in a Ni-Based Single Crystal Superalloy

SSRN Electronic Journal ◽

10.2139/ssrn.3399182 ◽

2019 ◽

Author(s):

B. Yin ◽

G. Xie ◽

L.H. Lou ◽

J. Zhang

Keyword(s):

Heat Treatment ◽

Single Crystal ◽

Single Crystal Superalloy ◽

Abnormal Increase ◽

Tcp Phase

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New Phases in a Multicomponent High Ruthenium Single Crystal Superalloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.655 ◽

2005 ◽

Vol 475-479 ◽

pp. 655-660 ◽

Cited By ~ 1

Author(s):

Q. Feng ◽

L.J. Rowland ◽

T.M. Pollock

Keyword(s):

Single Crystal ◽

Dendritic Structure ◽

Thermal Exposure ◽

Single Crystal Superalloy ◽

Heusler Phase ◽

Topologically Close Packed ◽

Tcp Phases ◽

Δ Phase

Three unusual Ru-rich phases have been identified in a multicomponent Ni-base single crystal superalloy, including a L21 Ru2AlTa Heusler phase, a B2 RuAl phase and a hcp Re(Ru)-rich δ phase. These phases have their own preferential precipitation location within the dendritic structure. No conventional topologically-close-packed (TCP) phases have been observed with thermal exposure at 950oC for 1500 hours.

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