Influence of Atomic Size Factors on the Phase Stability of Laves Phase in Nb-Cr-Ni-Al and Nb-V-Ni-Al Phase Diagrams

Yamanouchi, Takuya; Miura, Seiji

doi:10.2320/matertrans.mj201604

Cited by 9 publications

(5 citation statements)

References 35 publications

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“…This question of so-called site preference 1 was discussed, for example, in Refs. [16,17,[82][83][84][85][86][87]. Upon adding a third element C to a Laves AB 2 , i.e., moving into the ternary system A-B-C, C may substitute either A or B to form a solid solution of the general formula (A 1-x C x )(B 1-y C y ) 2 , if we, for a moment neglect the possibility of A and B occupying the opposite sublattices.…”

Section: Stability and Site Preferencementioning

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: Stability and Site Preferencementioning

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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“…Therefore, it can be concluded that Ti(Co, Cr, Fe, Mn) 2 might be expected to form a Laves phase, and Ti atoms mainly occupy the A-site. It is known that the stability of Laves-type phase is dominated by the atomic size difference between large A-site elements and small B-site elements [30][31][32]. The Laves phase has been confirmed in a wide range 1.05 < r A /r B < 1.68 , although the ideal size difference ratio is r A /r B = 1.225 ,.…”

Section: Phase Stability Of Each Constituent Phasementioning

confidence: 98%

The effect of titanium and silicon addition on phase equilibrium and mechanical properties of CoCrFeMnNi-based high entropy alloy

Yamanaka

Ikeda

Miura

2021

Journal of Materials Research

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The effects of Ti and Si addition on the phase equilibrium and mechanical properties of the equiatomic CoCrFeMnNi high entropy alloy (Cantor alloy) were investigated. The phase equilibrium at 1000 °C was determined from the result of X-ray diffraction and electron probe micro-analysis. Ti addition stabilizes the $$\sigma$$ σ phase, A12 phase and C14-Laves phase, while Si addition stabilizes the A13 phase. The phase relationships were represented by projection onto (Co, Fe, Mn, Ni)–Cr–X(Ti or Si) isothermal ternary cross-section at 1000 °C in Co–Cr–Fe–Mn–Ni–X senary system. Tensile tests were conducted on Cantor-based fcc single solid solution alloys with Ti or Si dissolution at room temperature. The 0.2% yield strength and ultimate tensile strength increased with either element addition. The Ti-added alloy showed higher strength than the Si-added alloy. The difference in ductility in the alloys is related to their strain hardening behavior in the higher strain range. Graphic abstract

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“…Some AB 2 -type intermetallic Laves phases with topologically close-packed (TCP) structures are classified into such an intermetallic compound group. 3,4) There are three major types of Laves phases: the cubic C15 phase, the hexagonal C14 phase and the dihexagonal C36 phase. However, the limitation of these intermetallics is their poor room-temperature toughness.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution and Mechanical Properties of a Three-Phase Alloy in the Cr–Mo–Nb System

Ikeda

Horiuchi

et al. 2019

Mater. Trans.

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A new three-phase alloy of 50Cr30Mo20Nb (at%) was studied based on the CrMoNb ternary phase diagram, and was composed of a Cr-rich BCC 1 phase, a Mo-rich BCC 2 phase and a NbCr 2 Laves phase after heat treatment at around 1523 K or lower. A supersaturated BCC single-phase solid solution alloy obtained by homogenization at 1973 K for 1 h underwent microstructural evolution during heat treatment at 1473 K. Intragranular precipitation of the Cr-rich BCC 1 phase occurred, which led to the formation of an alternating BCC 1 /BCC 2 two-phase microstructure through a discontinuous precipitation process, followed by precipitation of the Laves phase at the BCC 1 /BCC 2 interphase boundaries. At a higher temperature of 1523 K, a similar microstructure was observed, with increased BCC decomposition and Laves precipitation rates, while the alloy consisted of BCC and Laves phases at 1773 K. The mechanical properties of alloys heat treated at 1473 K for various periods after the solid-solution treatment were also investigated. A maximum fracture strength of 1493 MPa and a minimum hardness of 773 « 7 HV were obtained for an alloy aged for 24 h, where the BCC 1 /BCC 2 two-phase microstructure dominated. The Vickers hardness of an alloy aged for 72 h, which had a fine-grained microstructure that included the Laves phase, was 839 « 8 HV under a load of 0.5 kgf, and no obvious microcracks were observed. [

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Influence of Atomic Size Factors on the Phase Stability of Laves Phase in Nb-Cr-Ni-Al and Nb-V-Ni-Al Phase Diagrams

Abstract: Fig. 1 bcc ss /B2/Laves three-phase elds in quasi-ternary phase diagrams of the (a) Ta-Cr-NiAl, 13) (b) Ta-V-NiAl, 14) (c) Ta-Mo-NiAl, 15) and (d) Nb-Mo-NiAl 16) systems.

Cited by 9 publications

References 35 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

The effect of titanium and silicon addition on phase equilibrium and mechanical properties of CoCrFeMnNi-based high entropy alloy

Microstructural Evolution and Mechanical Properties of a Three-Phase Alloy in the Cr–Mo–Nb System

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