Structure and properties of high-entropy CoCrCuFeNiSn x alloys

2019

JPhysElectron

Self Cite

Molecular dynamics simulation of the solidification behavior of AlCoCuFeNi nanowire was carried out basing on the embedded atom potential with different cooling rates (1∙1011 , 1∙1012, and 1∙1013 K/s). To simulate an infinite nanowire, a periodical boundary condition along the nanowire axis direction was applied. The crystallization of the nanowire was characterized by studying the temperature dependence of the potential energy. The adaptive common neighbor analysis (CNA) was performed and the radial distribution function (RDF) was calculated to determine the structure and lattice parameters of phases of the AlCoCuFeNi nanowire. It has been shown that the final structure of investigated nanoparticle changes from amorphous to crystalline with decreasing of the rate of cooling.

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of the solidification of AlCoCuFeNi high–entropy alloy nanowire

2019

JPhysElectron

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“…At the same time, the purposeful selection of components allows one to obtain the structure of HEA, which is a combination of a simple solid solution characterized by high plasticity and intermetallic compounds (σ phase, Laves phases) characterized by high hardness [1,2]. The HEAs are characterized by unique structures and a number of useful service characteristics, such as hardness, wear-resistance, resistance to oxidation, corrosion, and ionizing radiation, high thermal stability and biocompatibility [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

The effect of cooling rate on the magnetic properties of Cu-Fe-Ni multicomponent alloys with Al and Si additions

Башев

2018

JPhysElectron

Self Cite

The paper explores the structure and magnetic properties of multicomponent high-entropy Al-Cu-Fe-Ni-Si alloys in as-cast and splat-quenched state. This alloy system is characterized by the absence of expensive components, such as Co, V, Mo, Cr, usually used for the production of high-entropy alloys while its characteristics are not inferior to those of more expensive alloys. Components of the studied high-entropy alloys were selected taking into account both criteria for designing and estimating their phase composition, which are available in the literature and based on the calculations of the entropy and enthalpy of mixing, and the difference between atomic radii of components as well. The alloy films were fabricated by a known technique of splat-quenching. A cooling rate estimated by film thickness was ~ 106 K/s. Experimental results reveal that the studied alloys except the Al0.5CuFeNi one are multiphase, with the structure consisting of disordered BCC and FCC solid solutions. The Al0.5CuFeNi alloy has only FCC phase. The leading role in determining the type of solid solution formed in the studied high-entropy films obviously plays an element with the highest melting point. All of the investigated multicomponent films are soft magnetic materials as indicated by low values of coercivity, while most of the as-cast alloys are hard-magnetic.

“…Currently, the following approaches are used to obtain new metallic materials with improved characteristics: 1) applying of modern methods of fast crystallization with cooling rates from 10 6 K/s (liquid quenching) to 10 12 K/s (vapor quenching) [1][2][3][4]; 2) evaluation of properties of the crystal lattices at the atomic level [5,6]; 3) the development of multicomponent high-entropy alloys [7,8]; 4) the use of practical experience in quenching methods improving [9].…”

mentioning

confidence: 99%

Influence of Liquid Quenching on Phase Composition and Properties of Be-Si Eutectic Alloy

Башев

Ryabtsev

et al. 2020

EEJP

By the method of quenching from the liquid state (splat-quenching), it is first revealed the formation of mixture of metastable supersaturated substitutional solid solutions in the eutectic alloy Be-33at.% Si. Cast samples are obtained by pouring melt into a copper mold. High cooling rates during liquid quenching are achieved throw the well-known splat-cooling technique by spreading a drop of melt on the inner surface of a rapidly rotating, heat-conducting copper cylinder. The maximum cooling rates are estimated by the foil thickness. The melt cooling rates (up to 108К/s), used in the work, are sufficient to form amorphous phases in some eutectic alloys with similar phase diagrams, but it is found those rates are insufficient to obtain them in the Be-Si eutectic alloy. The X-ray diffraction analysis is carried out on a diffractometer in filtered Cobalt Ka radiation. Microhardness is measured on a micro-durometer at a load of 50 g. The electrical properties, namely the temperature dependences of relative electrical resistance, are studied by the traditional 4-probe method of heating in vacuum. The accuracy of determining the crystal lattice period of the alloy, taking into account extrapolation of the reflection angle by 900, is ± 3•10-4 nm. It is found that even at extremely high rate of quenching from the melt, instead of the amorphous phase formation, the occurrence of two supersaturated substitutional solid solutions, based on Beryllium and Silicon, is revealed. This fact is established by the obtained dependences of their lattice periods values on the alloying element content. So, during the formation of metastable eutectic structure, a supersaturated with Beryllium solid solution of Silicon has period a = 0.5416 nm, and a supersaturated with Silicon solid solution of low-temperature hexagonal Beryllium has periods a = 0.2298 nm, c = 0.3631 nm. The positive role of the liquid quenching method in increasing the level of mechanical characteristics (microhardness and microstresses) in rapidly cooled Be-Si films is shown. It has been demonstrated that the difference in the atomic radii of the elements significantly affects the distortion of crystal lattices of the formed supersaturated solid solutions, and a significant value of microstresses (second-order stresses) in the Silicon lattice supersaturated with Beryllium is estimated, which, of course, leads to a significant increase in the microhardness, namely: there is an increase in microhardness in the Be-Si alloy under the conditions of applied method of quenching from the liquid state by more than 1.7 times compared to cast eutectic alloy and more than 6 times higher in comparison with the eutectoid cast Iron-Carbon alloy. The obtained polytherm of electrical resistance of the alloy under conditions of continuous heating in vacuum confirms the metastable nature of obtained new phases during quenching from the liquid state.