Effect of growth rate on the tensile properties of DS NiAl/Cr(Mo) eutectic alloy produced by liquid metal cooling technique

Liang, Yue; Xie, Yanhui; Sheng, Li Yuan; Zhou, Lan; Hu, Z. Q.

doi:10.1016/j.intermet.2009.08.002

Cited by 13 publications

(4 citation statements)

References 9 publications

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“…The extraordinary work hardening behavior of the EHEA is reflected when comparing with NiAl-based alloys ( Fig. 6c ), where the ratios of fracture strength to yield strength (σ UTS /σ 0.2 ) are normally in the range of 1 ~ 2 14 15 16 17 18 19 20 21 22 23 24 25 26 , while the EHEA has a σ UTS /σ 0.2 (note it is the proof stress here) close to 16. Such a high σ UTS /σ 0.2 is also far beyond those of conventional alloys, which are in the range of 1 ~ 3 27 28 29 .…”

Section: Resultsmentioning

confidence: 94%

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A Promising New Class of High-Temperature Alloys: Eutectic High-Entropy Alloys

Dong

Guo

et al. 2014

Sci Rep

1,143

243

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High-entropy alloys (HEAs) can have either high strength or high ductility, and a simultaneous achievement of both still constitutes a tough challenge. The inferior castability and compositional segregation of HEAs are also obstacles for their technological applications. To tackle these problems, here we proposed a novel strategy to design HEAs using the eutectic alloy concept, i.e. to achieve a microstructure composed of alternating soft fcc and hard bcc phases. As a manifestation of this concept, an AlCoCrFeNi2.1 (atomic portion) eutectic high-entropy alloy (EHEA) was designed. The as-cast EHEA possessed a fine lamellar fcc/B2 microstructure, and showed an unprecedented combination of high tensile ductility and high fracture strength at room temperature. The excellent mechanical properties could be kept up to 700°C. This new alloy design strategy can be readily adapted to large-scale industrial production of HEAs with simultaneous high fracture strength and high ductility.

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Section: Resultsmentioning

confidence: 94%

“…To further showcase the excellent balanced mechanical properties of this newly developed EHEA as candidate high-temperature alloys, a comparison between it and NiAl and NiAl/Cr(Mo) eutectic alloys 14 15 16 17 18 19 20 21 22 23 24 25 26 is given in Fig. 6 .…”

Section: Resultsmentioning

confidence: 99%

A Promising New Class of High-Temperature Alloys: Eutectic High-Entropy Alloys

Dong

Guo

et al. 2014

Sci Rep

1,143

243

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“…To improve the fracture toughness and strength of NiAl-based materials, many techniques have been tried and many NiAl-based alloys or composites have been designed and fabricated [16][17][18][19]. Among these NiAl-based materials, the ceramic-particle-strengthened NiAl-based composites exhibit high strength, while the fiber-or lamella-phase-strengthened alloys demonstrate better fracture toughness [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Influence of Strengthening Elements and Heat Treatment on Microstructure and Fracture Toughness of NiAl-Cr(Mo)-Based Eutectic Alloy

Wang

Xie

et al. 2023

Materials

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Due to their potential improvement of high-temperature properties, the refractory metal hafnium (Hf) and the rare earth holmium (Ho) have attracted much attention. In the present research, NiAl-Cr(Mo) eutectic alloys with different Ho and Hf additions were fabricated by conventional smelting method and heat-treated to study the synergetic influence of strengthening elements and heat treatment. The samples were characterized using XRD, SEM, and TEM, and the three-point bending test was performed to obtain fracture toughness. The results demonstrate that Hf addition leads to the formation of Ni2AlHf Heusler phase and that Ho promoted the formation of Ni2Al3Ho phase. The microstructure of the alloy is affected by thermal treatment, with the coarsening of eutectic lamellae after heat treatment. The mechanical properties are improved by Hf and Ho additions, with increased fracture toughness. Overall, this study provides insights into the microstructure and properties of NiAl-Cr(Mo) eutectic alloys and highlights the potential of Hf and Ho addition to improve room-temperature properties. Specifically, the as-cast NiAl-Cr(Mo)-Hf eutectic alloy contains a relatively fine NiAl/Cr(Mo) eutectic lamella but coarse eutectic cell with Ni2AlHf phase embellished along the cell boundary. Minor Ho addition induces the formation of Ni2Al3Ho phase, which leads to the coarsening of the intercellular region but contributes to the refining of eutectic cell. In addition, the synergetic effect of Ho and Hf promotes the precipitation of Ni2Al3Ho and Ni2AlHf phases in the intercellular zone and increases the interface dislocations. Heat treatment benefits the solid solution of Ni2Al3Ho and Ni2AlHf phases, which improves their size and distribution by secondary precipitation. The Ni2AlHf phase in the NiAl-Cr(Mo)-Hf eutectic alloy becomes fine and uniformly distributed, but the NiAl/Cr(Mo) eutectic lamella in the eutectic cell becomes coarse. In comparison, heat treatment mainly optimizes the size and distribution of the Ni2Al3Ho and Ni2AlHf phases in the NiAl-Cr(Mo)-Hf-Ho eutectic alloy. Furthermore, heat treatment helps to eliminate the interface dislocations in the large NiAl precipitates and the NiAl/Cr(Mo) phase interfaces, which also contributes to fracture toughness by decreasing stress concentration. Minor Ho addition decreases the fracture toughness of as-cast NiAl-Cr(Mo)-Hf eutectic alloy from 6.7 to 6.1 MPa·m1/2, which should be ascribed to the coarsened intercellular region including aggregated Ni2Al3Ho and Ni2AlHf phases. However, minor Ho-doped NiAl-Cr(Mo)-Hf eutectic alloy obtained the highest fracture toughness of 8.2 MPa·m1/2 after heat treatment. This improved fracture toughness should be mainly attributed to the refined and well-distributed Ni2Al3Ho and Ni2AlHf phases in the heat-treated NiAl-Cr(Mo)-Hf-Ho eutectic alloy.

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“…Hence, numerous attempts have been made in recent years to overcome this problem. The common methods employed to improve the RT ductility of nickel aluminide intermetallics include: grain refining, improving the slip systems, and alloying [8][9][10][11][12][13][14][15]. Mechanical alloying (MA) can provide all those mentioned above simultaneously, therefore, this technique has been extensively applied to synthesize nickel aluminide intermetallic.…”

Section: Introductionmentioning

confidence: 99%