Understanding the mechanical behaviour and the large strength/ductility differences between FCC and BCC AlxCoCrFeNi high entropy alloys

Joseph, Jithin; Stanford, Nicole; Hodgson, Peter; Fabijanic, Daniel

doi:10.1016/j.jallcom.2017.08.067

Cited by 186 publications

(52 citation statements)

References 48 publications

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“…Five different phases with the chemical composition given in Table 1 can be well identified within the compression specimens. Based on the EDS measurements and recent work of Zhang et al [25] and Joseph et al [26], the primary solidification phase is the most probably fcc solid solution (region 1), as shown in Fig. 4c.…”

Section: Initial Microstructure Of Compression Specimensmentioning

confidence: 81%

Effect of anisotropic microstructure on high-temperature compression deformation of CoCrFeNi based complex concentrated alloy

Stamborska¹,

Lapin²

2018

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The effect of anisotropic as-cast microstructure on high-temperature compression deformation of multiphase Co24Cr19Fe24Ni19Al8(Ti,Si,C)6 (at.%) complex concentrated alloy (CCA) derived from a single phase CoCrFeNi based high entropy alloy (HEA) was studied at temperatures ranging from 750 to 900 • C. The highly anisotropic microstructure composed of several columnar grains with [100] crystallographic direction parallel or nearly parallel to the load axis leads to asymmetric barrelled shapes of the compression specimens with multiple protuberances on the barrelled surfaces. The experimental barrelled shapes differ from the numerically calculated ones. The deformation curves exhibit strain hardening stage which is followed by a deformation at a constant flow stress at all studied temperatures. The work hardening rate (WHR) first increases with increasing strain. After achieving a peak value, the WHR decreases and achieves values around zero corresponding to the steady-state deformation. The finite element analysis (FEA) of 3D distribution of local equivalent strains and stresses corresponds qualitatively quite well to the observed structural changes within the barrelled specimens. K e y w o r d s : complex concentrated alloys, high-entropy alloys, anisotropy, plastic deformation, mechanical properties, finite element modelling

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Section: Initial Microstructure Of Compression Specimensmentioning

confidence: 81%

Effect of anisotropic microstructure on high-temperature compression deformation of CoCrFeNi based complex concentrated alloy

Stamborska¹,

Lapin²

2018

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“…Lastly there is a need to develop a shared, standardized data repository that contains feed material and AM material standards to assist the selection of proper AM materials. In fact, pioneer research [223,224] has shown that using DLD, HEA alloys with selected compositions can be fabricated with added advantages of less segregation, reduced brittle phases, and grain refinement. Researchers must play a role in disseminating results to the public by investigating new AM materials, materials with tailored properties, and their resulting microstructures.…”

Section: Tailored Materials and Microstructuresmentioning

confidence: 99%

Laser‐Based Additive Manufacturing Technologies for Aerospace Applications

2019

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Additive manufacturing (AM) is a transformative technology that has rapidly grown over the past decade. AM processes build parts layer by layer and have found applications in the aerospace, biomedical, and automotive fields. The technology holds particular promise for the aerospace industry due to the reduced process time, weight savings of parts, and opportunities for new material development. Herein, a review of laser-based AM processes, existing AM systems, and aerospace parts being fabricated is presented. It further explores the material properties and microstructure of printed samples with both powder bed fusion and direct energy deposition processes. The benefits and challenges associated with the widespread use of the technology are discussed with emphases on the aerospace sector. Finally, the steps required for parts produced by AM processes to become certified for use in aerospace applications are presented.

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“…78 A mixed fracture feature with regions of dimpled and faceted appearance is present in a fractured specimen for a direct-laser-fabricated Al 0.6 CoCrFeNi HEA, in which voids and cracks are formed at the fcc/bcc interface. 79 With the addition of Al, a homogenized AlCoCrFeNi HEA exhibits a transgranular fracture. 80 Cracks are FIG.…”

Section: Quasi-static Uniaxial Tensile Loadingmentioning

confidence: 99%

“…36,66 The CoCrFeMnNi HEA is fractured with ductile dimples nucleated at the oxides upon uniaxial-tension tests at RT, and apparent necking is noticed for the samples tested at 77 K. 13,67,68 Tension fracture in HEAs with a mixed fcc and bcc phase initiates at the interface between the two phases, and/or the precipitates at the grain boundaries. [79][80][81] HEAs with a bcc phase are compression-fractured by quasicleavage, 24,85 or intergranular fracture. 84,85 Brittle features are also observed in the recrystallized Al 0.1 CoCrFeNi and Al 0.3 CoCrFeNi HEAs after impact tests.…”

Section: Summary Of Present Researchmentioning

confidence: 99%