The fracture resistance of directionally solidified dual-phase NiAl reinforced with refractory metals

Heredia, F.E.; He, Ming; Lucas, G.E.; Evans, A.G.; Dève, H.E.; Konitzer, D.G.

doi:10.1016/0956-7151(93)90079-8

Cited by 107 publications

(33 citation statements)

References 16 publications

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“…in a NiAl/Mo alloy with a rod eutectic microstructure. [31] These have been described as crack trapping "trails" by Heredia et al, [30] where the toughening mechanism was observed, as evidenced by an examination of Figure 16(c), which shows that the (Cr,Mo) platelets have necked only in attributed to crack bridging. However, in the present case, significant crack bridging by the (Cr,Mo) plates was not a few areas of the fracture surface.…”

Section: Fracture Morphologiesmentioning

confidence: 86%

“…In this case, K Q increases with increasing in the range 0 Յ to between 6.5 and 8.2 MPaΊm above a growth speed of 127 mm h Ϫ1 . In contrast, the mean fracture toughness for Յ 0.5 from about 6 MPaΊm for binary polycrystalline NiAl [30] to an approximately constant average value of the Ni-33Al-31Cr-3Mo alloy increased from a value of about 20 MPaΊm, [9] this conclusion is also applicable to rod eutectic microstructures. However, as discussed later, significant (c) toughening is achieved only when the (Cr,Mo) plates are …”

Section: Microstructural Observations Of Both the Longitudinal Andmentioning

confidence: 90%

“…The average fracture-toughness values for the Ni-33Al-33Cr-1Mo specimens grown at (Figure 11(d)). The fracture toughness values for polycrystalline NiAl [30] and for a NiAl/(Cr,Mo) alloy [31] are also speeds between 7.6 and 127 mm h Ϫ1 were fairly constant varying between 14.3 and 17.1 MPaΊm but dropped sharply included in Figure 11(d) for the sake of completeness. In this case, K Q increases with increasing in the range 0 Յ to between 6.5 and 8.2 MPaΊm above a growth speed of 127 mm h Ϫ1 .…”

Section: Microstructural Observations Of Both the Longitudinal Andmentioning

confidence: 98%

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Effect of directionally solidified microstructures on the room-temperature fracture-toughness properties of Ni-33(at. pct)Al-33Cr-1Mo and Ni-33(at. pct)Al-31Cr-3Mo eutectic alloys grown at different solidification rates

Raj

Salem

Locci

et al. 2002

Metall Mater Trans A

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Directionally solidified (DS) Ni-33(at. pct)Al-33Cr-1Mo and Ni-33(at. pct)Al-31Cr-3Mo eutectic alloys were grown at different rates varying from 7.6 to 508 mm h Ϫ1 . The microstructures consisted of eutectic colonies with parallel lamellar NiAl/(Cr,Mo) plates for solidification rates at and below 12.7 mm h Ϫ1 . Cellular eutectic microstructures were observed at higher solidification rates, where the plates exhibited a radial pattern. Room-temperature fracture-toughness tests were conducted using a modified ASTM E-399 technique. The average fracture-toughness values for specimens with planar eutectic and cellular microstructures were about 12 to 15 and 17 MPaΊm, respectively, for both alloys. However, the Ni-33(at. pct)Al-33Cr-1Mo specimens grown at and above 254 mm h Ϫ1 exhibited fracture toughness values of about 8 MPaΊm due to the presence of short (Cr,Mo) plates. The fracture toughness values for the Ni-33(at. pct)Al-31Cr-3Mo alloy were also correlated with quantitative microstructural data in an attempt to identify the relevant elements of the microstructure determining resistance to fracture. A phenomenological fracture model is presented in an attempt to rationalize the present observations.

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Section: Fracture Morphologiesmentioning

confidence: 86%

Section: Microstructural Observations Of Both the Longitudinal Andmentioning

confidence: 90%

Section: Microstructural Observations Of Both the Longitudinal Andmentioning

confidence: 98%

See 1 more Smart Citation

Effect of directionally solidified microstructures on the room-temperature fracture-toughness properties of Ni-33(at. pct)Al-33Cr-1Mo and Ni-33(at. pct)Al-31Cr-3Mo eutectic alloys grown at different solidification rates

Raj

Salem

Locci

et al. 2002

Metall Mater Trans A

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“…5, May 1995 crack front does not have continuous access to the brittle matrix. 6 Indeed, promising room temperature fracture toughness values, much greater than that of binary NiAl, have been measured for aligned material produced by directional solidification of the lamellar NiAl-28Cr-6Mo eutectic. 1 The directionally solidified NiAl-28Cr-6Mo has an average fracture toughness of 21 MPa N /rrf, 1 while polycrystalline NiAl has a fracture toughness of approximately 6 MPa^/rrF.…”

Section: Introductionmentioning

confidence: 99%

Deformation and fracture of a directionally solidified NiAl–28Cr–6Mo eutectic alloy

et al. 1995

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A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a 〈111〉 growth direction for both the NiAl and (Cr,Mo) phases. The interphase boundary between the eutectic phases was semicoherent and composed of a well-defined dislocation network. In addition, a fine array of coherent NiAl precipitates was dispersed throughout the (Cr, Mo) phase. The eutectic morphology was stable at 1300 K with only coarsening of the NiAl precipitates occurring after heat treatment for 1.8 ks (500 h). Fracture of the aligned eutectic is characterized primarily by a crack bridging/renucleation mechanism and is controlled by the strength of the semicoherent interface between the two phases. However, contributions to the toughness of the eutectic may arise from plastic deformation of the NiAl phase and the geometry associated with the fracture process.

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“…[4][5][6] The extrinsic toughening mechanisms like crack trapping, crack deflection, interface debonding and crack bridging are responsible for the improvement in toughness. The creep-resistant secondary phases including refractory metal and Laves phase (NiAlX, X=Ta, Nb) provide the improvement of high temperature strength for the eutectic systems.…”

Section: Introductionmentioning

confidence: 99%

Creep Characteristic of NiAl-9Mo Eutectic Alloy

et al. 2004

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The creep behavior of NiAl-9Mo eutectic alloy has been studied in an effort to understand the characteristic that the alloy exhibits of the low stress exponent of 4.75 and the high apparent activation energy of 410 kJ/mol during the steady-state creep of under the test conditions. The material exhibits threshold behavior with a threshold stress of 17.9 MPa. TEM observation reveals that the creep deformation is mainly governed by dislocation climb in NiAl matrix phase. Large recoverable strain is observed after unloading under the transient creep and increases with the increase of stress or temperature. It exhibits an activation energy 232 kJ/mol, suggesting the processes is controlled by the flow behavior of the matrix phase. The apparent creep activation energy under constant stress is a combination of the creep flow activation energy of the matrix and the activation energy for the damage process at the phase interface.

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The fracture resistance of directionally solidified dual-phase NiAl reinforced with refractory metals

Cited by 107 publications

References 16 publications

Effect of directionally solidified microstructures on the room-temperature fracture-toughness properties of Ni-33(at. pct)Al-33Cr-1Mo and Ni-33(at. pct)Al-31Cr-3Mo eutectic alloys grown at different solidification rates

Effect of directionally solidified microstructures on the room-temperature fracture-toughness properties of Ni-33(at. pct)Al-33Cr-1Mo and Ni-33(at. pct)Al-31Cr-3Mo eutectic alloys grown at different solidification rates

Deformation and fracture of a directionally solidified NiAl–28Cr–6Mo eutectic alloy

Creep Characteristic of NiAl-9Mo Eutectic Alloy

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