Nanocrystalline Ni–3.6 at.% P and its transformation sequence studied by atom-probe field-ion microscopy

Hentschel, Th; Isheim, Dieter; Kirchheim, R.; Müller, Felix L.; Kreye, H.

doi:10.1016/s1359-6454(99)00371-7

Cited by 154 publications

(56 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Except for the difference in amplitude, the absorption spectra of Ni 92 P 8 and Ni 90 P 10 are similar to that of Ni foil. However, the spectra of Ni 86 P 14 , Ni 80 P 20 and Ni 74 P 26 are very different from that of Ni foil, and only signal of a single frequency can be observed. …”

Section: Resultsmentioning

confidence: 91%

Effect of Phosphorus Content on Local Structures of NiP Amorphous Alloys

Song¹,

Zheng²,

Zhang³

et al. 2007

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. XAFS technique is used to determine the atomic and electronic structures of NiP amorphous alloys with different P concentrations prepared by chemical reduction method. From the radial structural function (RSF) obtained from EXAFS, it is found that the amorphous alloys with P content less than 10 at.% still present strong peaks corresponding to high coordination shells just like crystalline Ni. This indicates the prominent existence of Ni-rich phase with the fcc-structure, which is not remarkably modified by the P atoms. As the P content is as large as 14 at.%, only the first shell peak in the RSF can be observed and the higher shell peaks disappear. Therefore the sample is totally amorphous. The XANES results show that as the P concentration is above 26 at.%, charge transfers from Ni atoms to P atoms. For P concentration lower than 20at.%, on the contrary, charge transfers from P atoms to Ni atoms, and 3d electron density of Ni atoms reaches the maximum when P concentration is about 14~20 at.%.

show abstract

Section: Resultsmentioning

confidence: 91%

Effect of Phosphorus Content on Local Structures of NiP Amorphous Alloys

Song¹,

Zheng²,

Zhang³

et al. 2007

AIP Conference Proceedings

View full text Add to dashboard Cite

show abstract

“…4 Grain growth inhibition can be engineered from both kinetics and thermodynamics perspectives. 5,6 While the kinetic approach focuses on inputting 'pinning' agents along a grain boundary (GB), slowing migration by creating dragging forces, 7 the thermodynamic strategy targets a decrease in GB energy, the direct driving force for coarsening. 8 Several works have modeled the energetic stabilization of GBs, 2,[8][9][10] quantitatively describing the effect of a solute enrichment on the average GB energy of a system as follows:…”

Section: Introductionmentioning

confidence: 99%

Direct measurements ofquasi-zero grain boundary energies in ceramics

Nafsin

Castro

2016

J. Mater. Res.

View full text Add to dashboard Cite

Nanocrystalline bulk materials (also called nanograined materials) are intrinsically unstable due to the excess grain boundary (GB) free energies. Dopants designed to segregate to boundaries have been proposed to lower excess GB energies, increasing stability against coarsening and enabling nanostructure features to survive high temperature processing and operational environments. It has been theoretically proposed that the GB energy of a material can eventually become zero as a function of dopant concentration, signifying negligible driving force for growth-an infinitely stable nanomaterial. In this work we use ultrasensitive microcalorimetry to experimentally measure the absolute GB energy of gadolinium-doped nanocrystalline zirconia as a function of grain size and show that the energy can indeed reach a quasi-zero energy state (;0.05 J/m 2 ) when a critical GB dopant enrichment is achieved. This thermodynamic condition leads to unprecedented coarsening resistance, but is a temperature dependent function; since increasing temperatures deplete the GB as the dopant dissolves back in the crystalline bulk.

show abstract

Section: Introductionmentioning

confidence: 99%

“…These suggest that equilibrium solute segregation lowers the grain boundary energy to varying degrees. Experimentally, a reduction in the propensity for grain growth in nanocrystalline materials has been observed in a variety of binary alloys [21][22][23][24][25][26][27][28][29][30][31]. There are many indications in experimental systems that there is a "preferred" grain size which emerges during processing which is closely linked to the solute content [2,24,30,32,33]; this is considered significant evidence for a thermodynamic contribution to stabilization.…”

mentioning

confidence: 99%

“…The grain size that is stable against coarsening is correlated to the solute concentration in these systems, but the system also often exhibits instabilities with respect to phase separation. In particular, the precipitation of a second phase above a certain solute content disturbs the segregation state and can trigger rapid grain growth [30,31,[33][34][35].The above studies using experiment and simulation have achieved varying levels of success on specific individual alloy systems. However, the total number of alloy systems studied is small, and there is not enough information to be able to extrapolate to other alloying elements in unexplored systems.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Stability of binary nanocrystalline alloys against grain growth and phase separation

2013

View full text Add to dashboard Cite

Grain boundary segregation has been established through both simulation and experiments as a successful approach to stabilize nanocrystalline materials against grain growth. However, relatively few alloy systems have been studied in this context; these vary in their efficacy, and in many cases the stabilization effect is compromised by second phase precipitation. Here we address the open-ended design problem of how to select alloy systems that may be stable in a nanocrystalline state. We continue the development of a general "regular nanocrystalline solution" model to identify the conditions under which binary nanocrystalline alloy systems with positive heats of mixing are stable with respect to both grain growth (segregation removes the grain boundary energy penalty) and phase separation (the free energy of the nanocrystalline system is lower than the common tangent defining the bulk miscibility gap). We calculate a "nanostructure stability map" in terms of alloy thermodynamic parameters. Three main regions are delineated in these maps: one where grain boundary segregation does not result in a stabilized nanocrystalline structure, one in which macroscopic phase separation would be preferential (despite the presence of a nanocrystalline state stable against grain growth), and one for which the nanocrystalline state is stable against both grain growth and phase separation. Additional details about the stabilized structures are also presented in the map, which can be regarded as a tool for the design of stable nanocrystalline alloys. Atomistic simulations on nanocrystalline alloys show that structural stabilization is contingent upon the distribution and character of the solute atom. A certain minimum concentration of solute is often found to be necessary for grain size stabilization, as for various solute species in simulated copper [11][12][13][14][15][16][17]. The efficacy of different solute species is variable, and in some studies has been related to the size difference between solute and solvent atoms [11][12][13]. However, in these studies, the grain boundaries are manually decorated with solute atoms, which may represent artificial segregation states. There have been fewer simulation works on systems where segregation is thermodynamic (by, e.g., Monte Carlo methods) [16][17][18][19][20]. These suggest that equilibrium solute segregation lowers the grain boundary energy to varying degrees. Experimentally, a reduction in the propensity for grain growth in nanocrystalline materials has been observed in a variety of binary alloys [21][22][23][24][25][26][27][28][29][30][31]. There are many indications in experimental systems that there is a "preferred" grain size which emerges during processing which is closely linked to the solute content [2,24,30,32,33]; this is considered significant evidence for a thermodynamic contribution to stabilization. The grain size that is stable against coarsening is correlated to the solute concentration in these systems, but the system also often exhibits instabilities w...

show abstract

Nanocrystalline Ni–3.6 at.% P and its transformation sequence studied by atom-probe field-ion microscopy

Cited by 154 publications

References 9 publications

Effect of Phosphorus Content on Local Structures of NiP Amorphous Alloys

Effect of Phosphorus Content on Local Structures of NiP Amorphous Alloys

Direct measurements ofquasi-zero grain boundary energies in ceramics

Stability of binary nanocrystalline alloys against grain growth and phase separation

Contact Info

Product

Resources

About