Formation of non-equilibrium ductile solid solutions and textures in NbCr2 bulks produced by mechanical milling and spark plasma sintering

Gao, Fei; Li, Kewei

doi:10.1016/j.jallcom.2020.154130

Cited by 15 publications

(4 citation statements)

References 70 publications

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“…In NbCr 2 Laves phase fabricated by spark plasma sintering (SPS), trace amounts of Nb and Cr solid solutions are observed to distribute among the grain boundaries. This kind of dual-phase toughening also resulted in an increase of fracture toughness, which, however, is still far from being sufficient for applications [634][635][636]. After a 500 h heat treatment at 1000°C, a (Ti,Mo)Fe 2 -based Laves phase alloy, which was slightly poor in Fe (nominal composition Fe-10Mo-30Ti in at.%), contained a volume fraction of about 12% of fine, * 250 nm sized, bcc-(Mo,Ti) precipitates.…”

Section: Figure 28mentioning

confidence: 99%

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

2020

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Laves phases with their comparably simple crystal structure are very common intermetallic phases and can be formed from element combinations all over the periodic table resulting in a huge number of known examples. Even though this type of phases is known for almost 100 years, and although a lot of information on stability, structure, and properties has accumulated especially during the last about 20 years, systematic evaluation and rationalization of this information in particular as a function of the involved elements is often lacking. It is one of the two main goals of this review to summarize the knowledge for some selected respective topics with a certain focus on non-stoichiometric, i.e., non-ideal Laves phases. The second, central goal of the review is to give a systematic overview about the role of Laves phases in all kinds of materials for functional and structural applications. There is a surprisingly broad range of successful utilization of Laves phases in functional applications comprising Laves phases as hydrogen storage material (Hydraloy), as magneto-mechanical sensors and actuators (Terfenol), or for wear- and corrosion-resistant coatings in corrosive atmospheres and at high temperatures (Tribaloy), to name but a few. Regarding structural applications, there is a renewed interest in using Laves phases for creep-strengthening of high-temperature steels and new respective alloy design concepts were developed and successfully tested. Apart from steels, Laves phases also occur in various other kinds of structural materials sometimes effectively improving properties, but often also acting in a detrimental way.

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Section: Figure 28mentioning

confidence: 99%

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

2020

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“…The TEM foil was prepared by ion polishing using PIPS-Model 691 and microscope Tescan Lyra 3 XMU FEG/SEM-FIB. The hardness and room-temperature fracture toughness of the sintered sample were measured by indentation tests as described in our previous papers [20,21]. As the raw powder used in the present was monolithic NbCr 2 , the indentations for hardness and fracture toughness measurements distributed homogeneously on the sample.…”

Section: Methodsmentioning

confidence: 99%

A new strategy to toughen NbCr₂ Laves phase

Jianyu

Wang

et al. 2021

Materials Science and Technology

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A new strategy to toughen NbCr2 Laves phase was proposed, in which ductile Cr and Nb solid solutions were incorporated by accelerating solute segregation within NbCr2 matrix using external applied pulsed electric current. A dense bulk consisting of ultrafine NbCr2 grains with abundant Cr and Nb solid solutions along the grain boundaries was produced by spark plasma sintering using monolithic NbCr2 starting powders. The formation of Cr and Nb solid solutions was attributed to the enhanced atomic transport, which facilitated the mobility of dislocations and the selective Joule heating. The fracture toughness of the sample achieved 11.3 MPa·m1/2, which was 9.4 times the as-cast NbCr2 (1.2 MPa·m1/2) and thus can be regarded as a new toughening mechanism.

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“…While there is a dearth of information on the behavior of solid solution Nb-Cr alloys in the literature, the mechanical properties of NbCr 2 -based alloys have been studied at length 1,3,4,[14][15][16][17][18][19][20][21][22][23][24][25] . As NbCr 2 exhibits high thermal stability and exceptional corrosion and creep resistance due to its highly-complex close-packed crystal structure 22 , material applications span a wide range.…”

Section: A First Step Towards Understanding Thermomechanical Behavior...mentioning

confidence: 99%

“…The work also concluded that dislocation motion occurred at high temperature due to a relaxation in the otherwise tightly-packed Laves-phase crystal structure, which created large Peierls forces for dislocation motion. In another experimental study utilizing spark plasma sintering, Gao et al 19 observed that crack propagation in Laves NbCr proceeded in a zigzag pattern, improving fracture toughness. Additional studies on Laves NbCr have included investigations of thermal properties.…”

Section: Introductionmentioning

confidence: 99%

A first step towards understanding thermomechanical behavior of the Nb-Cr system through interatomic potential development and molecular dynamics simulations

Heaton,

Samin

2024

Sci Rep

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Utilizing a preliminary interatomic potential, this work represents an initial exploration into the thermomechanical behavior of NbCr solid solutions. Specifically, it examines the effect of different amounts of Cr solute, for which information in the literature is limited. The employed interatomic potential was developed according to the embedded atom model (EAM), and was trained on data derived from density functional theory calculations. While the potential demonstrated reasonable accuracy and predictive power when tested, various results highlight deficiencies and encourage further development and training. Mechanical strength, heat capacities, thermal expansion coefficients, and thermal conductivities were found to decrease with Cr content. Elastic coefficients, too, were observed to be strongly dependent on Cr composition. The Pugh embrittlement criterion was not satisfied for any of the compositions and temperatures explored. Gibbs free energy calculations performed on C14, C15, and C36 NbCr$$_{2}$$ 2 allotropes predicted the C36 structure to be the most thermodynamically favorable across all investigated temperatures and it was found that C36 becomes increasingly more stable relative to the other two phases with increased pressure. The inability of this work to accurately capture the stability of the different Laves phases is most likely due to the shortcomings in the developed potential.

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Formation of non-equilibrium ductile solid solutions and textures in NbCr2 bulks produced by mechanical milling and spark plasma sintering

Cited by 15 publications

References 70 publications

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

A new strategy to toughen NbCr₂ Laves phase

A first step towards understanding thermomechanical behavior of the Nb-Cr system through interatomic potential development and molecular dynamics simulations

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