Interdiffusion and solid solution strengthening in Ni–Co–Pt and Ni–Co–Fe ternary systems

Divya, V.D.; Ramamurty, Upadrasta; Paul, Aloke

doi:10.1080/14786435.2013.765987

Cited by 21 publications

(11 citation statements)

References 25 publications

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“…In different composition ranges, the difference in data by one order of magnitude can easily be found [47]. Therefore, this study wrongly states that diffusion rate decreases because of entropy effect with the increase in a number of components.…”

Section: Estimation Of the Average Interdiffusion Coefficientsmentioning

confidence: 74%

A Mystery of "Sluggish Diffusion" in High-Entropy Alloys: The Truth or a Myth?

et al. 2018

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High entropy alloys (HEAs) are considered as a novel class of materials with a large number of components (five and more) available in equiatomic or nearly equatomic proportions.One of the characteristic properties of HEAs was believed to be so-called 'sluggish' diffusion that should be crucial for intended high-temperature technological applications. The faith on this myth instead of rigorous experimental analysis played such a dominant role that the first set of data on interdiffusion, in fact based on an improper analysis, were cited in hundreds of articles to state the presence of sluggishness of diffusion rates in high entropy alloys.In this review, the recent data on atomic diffusion in HEAs are presented and critically discussed. The discussion is focused on tracer diffusion which is already measured dominantly for polycrystalline, but in some cases for single crystalline high-entropy alloys. The radiotracer technique provided a unique access to the diffusion rates of elements in the alloys and in fortunate cases these transport quantities could be measured in a single experiment, as in the case of Co, Cr, Fe and Mn diffusion in the CoCrFeMnNi HEA.Alternatively, a rigorous analysis of the interdiffuson experiments, which provide the diffusion rates of chemical species, too, becomes more and more sophisticated for three and more elements in an alloy and it is challenging to derive physically sound quantities from a general multicomponent diffusion experiment. Most promising in this case is the diffusion couple technique, especially the so-called pseudo-binary approach. This approach is analyzed with a focus on the applicability and the possible errors induced if up-hill diffusion appears.In the overview, it is shown that atomic diffusion in HEAs cannot a priori be considered as sluggish and both atomic interactions as well as correlation effects are responsible for the observed trends. Even if estimated on the same homologous scale, the diffusion retardation induced by a 'high entropy' in FCC crystals is not simply proportional to the number of alloying components and it is shown to be similar to that induced by, e.g., the L1 2 ordering in a binary system. Furthermore, the importance of cross-correlations in diffusion of different species in HEAs is highlighted. * Since there is no consensus about the way to list the principal elements in HEAs (alphabetic order, periodic table order, atomic percentage, etc), we will use the simple alphabetic order, as e.g. CoCrFeMnNi for the Cantor system.

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Section: Estimation Of the Average Interdiffusion Coefficientsmentioning

confidence: 74%

A Mystery of "Sluggish Diffusion" in High-Entropy Alloys: The Truth or a Myth?

et al. 2018

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“…According to a recent report [ 46 ], the molar volume V m of the Co–Ni alloys can be expressed by the linear relation ( V m = N Co × V Co + N Ni × V Ni ), which has a minor effect on the calculations of the interdiffusion flux. Here, the molar volumes for pure Ni ( V Ni ) and Co ( V Co ) were set to be 6.6 × 10 −6 m 3 /mol and 6.7 × 10 −6 m 3 /mol [ 35 ], respectively. A composition ratio Y at the distance coordinate x ’ is defined by,

…”

Section: Methodsmentioning

confidence: 99%

“…Thus, the precise measurement of “true” interdiffusivities is very difficult in this case. While for the pressing diffusion couple techniques, several approaches are often implemented, such as by engaging a special fixture [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ], adopting a friction welding technique [ 37 ], using a uniaxial hot-pressing technique [ 38 , 39 , 40 ], or by invoking a hot isostatic pressing (HIP) technique [ 41 ]. However, due to the narrow contact area between the two end–members, the applied stress on the samples cannot be neglected as “zero”, and thus it also affects the determined interdiffusivities.…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach to Eliminate the Effect of External Stress on Interdiffusivity Measurement

Chen

Zhang

2017

Materials

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In this paper, the interdiffusivities in fcc Co–Ni alloys at 1373 K due to different types of diffusion couple experiments were firstly re-calculated via the unified Wagner method based on the measured composition profiles. Their maximum difference due to different approaches for diffusion couple preparation was found to be larger than one order of magnitude. Then, a comprehensive analysis on the effect of different preparation methods was performed. After that, a two-step diffusion couple technique in combination with the pragmatic numerical inverse method was proposed to determine the accurate interdiffusivities by eliminating the effect of external stress. Such a novel approach was successfully applied in the binary fcc Co–Ni alloys for demonstration purposes. Moreover, it is anticipated that such novel approach can be utilized as the standard method for accurate interdiffusivity measurement, and the resultant accurate interdiffusivities in different alloys may serve as a benchmark for the later experimental and theoretical studies.

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“…It has, however, only been used to a limited extent to study the SSH behavior. [9,11,13] For example, Zhao [13] and Divya et al [11] used the DC-NI method to obtain H-c data in a few Ni-based binary and ternary alloy systems. However, these studies restricted their analyses to only qualitative comments on the SSH potency of various elements.…”

Section: Introductionmentioning

confidence: 99%

“…In this context, the diffusion couple (DC) approach combined with smallscale testing methods such as nanoindentation and/or micropillar compression holds great promise. [6][7][8][9][10][11][12][13][14] By means of the DC method, a library of compositions is generated in the interdiffusion zones, and the compositional analysis along these zones is performed with a high degree of accuracy by employing techniques such as electron probe microanalysis (EPMA). The interdiffusion zones are then probed for hardness, H, by employing nanoindentation (NI), and H as a function of solute concentration, c, is obtained.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Solid-Solution Hardening in Several Binary Alloy Systems Using Diffusion Couples Combined with Nanoindentation

Kadambi

Divya

Ramamurty

2017

Metall Mater Trans A

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Analysis of solid-solution hardening (SSH) in alloys requires the synthesis of large composition libraries and the measurement of strength or hardness from these compositions. Conventional methods of synthesis and testing, however, are not efficient and high-throughput approaches have been developed in the past. In the present study, we use a high-throughput combinatorial approach to examine SSH at large concentrations in binary alloys of Fe-Ni, Fe-Co, Pt-Ni, Pt-Co, Ni-Co, Ni-Mo, and Co-Mo. The diffusion couple (DC) method is used to generate concentration (c) gradients and the nanoindentation (NI) technique to measure the hardness (H) along these gradients. The obtained H-c profiles are analyzed within the framework of the Labusch model of SSH, and the c 2=3 dependence of H predicted by the model is found to be generally applicable. The SSH behavior obtained using the combinatorial method is found to be largely consistent with that observed in the literature using conventional and DC-NI methods. This study evaluates SSH in Fe-, Ni-, Co-, and Pt-based binary alloys and confirms the applicability of the DC-NI approach for rapidly screening various solute elements for their SSH ability.

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Interdiffusion and solid solution strengthening in Ni–Co–Pt and Ni–Co–Fe ternary systems

Cited by 21 publications

References 25 publications

A Mystery of "Sluggish Diffusion" in High-Entropy Alloys: The Truth or a Myth?

A Mystery of "Sluggish Diffusion" in High-Entropy Alloys: The Truth or a Myth?

A Novel Approach to Eliminate the Effect of External Stress on Interdiffusivity Measurement

Evaluation of Solid-Solution Hardening in Several Binary Alloy Systems Using Diffusion Couples Combined with Nanoindentation

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