Interphase boundary precipitation in a Ti-1.7 at. pct Er alloy

Kral, Milo V.; Hofmeister, William; Wittig, J. E.

doi:10.1007/s11661-997-0006-9

Cited by 5 publications

(7 citation statements)

References 27 publications

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“…Therefore, at any given time, t, the equations can be thought of as a set of ''static'' equilibrium equations by neglecting inertia forces and damping forces. This approach is used in most transient numerical models [5,6], and is efficient for the situations where higher-order dynamic effects are negligible. Figure 2 shows the program flowchart.…”

Section: Transient Analysis Of Sliding Contactmentioning

confidence: 99%

Transient analysis of sliding contact of layered elastic/plastic solids with rough surfaces

Peng

Bhushan

2003

Microsystem Technologies

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Based on the boundary element method (BEM) and a variational principle, a numerical model is developed to analyze the time -transient sliding contact of two layered elastic/plastic solids. Two cases are considered: one is the loading/sliding/unloading of a rough surface on a smooth surface, and the other is of two rough surfaces. Contact statistics, contact pressure profile and stress distribution are predicted at each time step with updated surface roughness. The results are used to study the effect of surface roughness, physical properties of the layer and the substrate, and lubricant film thickness on friction, stiction, and wear. Discussion on the integration of this contact model into advanced tribological models, e.g., wear model, is also presented. IntroductionThe deposition of layers is an effective way to improve the tribological performance of elastic/plastic solids with rough surfaces. For example, the Diamondlike carbon overcoat is used in magnetic head-disk interface to prevent wear and corrosion. In order to achieve the optimum performance of the layered structure, its contact mechanism has to be studied. Analytical methods usually are not feasible due to the complex nature of the contact problem. Numerical models are widely used to simulate the contact with the variation of contact parameters, thus are effective ways to study the contact mechanics. A comprehensive review of contact models has been presented in [1].However, current numerical models focus more on the static contact mechanism, e.g., normal contact and quasisliding contact. The transient sliding contact of two layer solids with rough surfaces, as shown in Fig. 1, has rarely been studied. Although the static models can predict a general trend of layer effect and surface roughness on the contact performance, the results are lack of relationship with the time history and very difficult to be compared with the experimental results.In this paper we extend a three-dimensional static contact model [1-4] to include a time factor as well. This three-dimensional numerical model was developed to analyze the quasi-sliding contact of two layered elastic/perfectly plastic solids with rough surfaces (multi-asperity contact). By performing a series of quasi-sliding analyses in a time sequence, with updated contact parameters at each specific time point, the model is extended from quasisliding contact (static) analysis to sliding contact (transient) analysis. Transient response, such as time-varying displacements and stresses, are predicted. This analysis provides a new insight of the surface evolution during the sliding contact of two rough surfaces and is critical in problems such as ''wear-in'' process of the pseudo-contact magnetic recording. BEM contact analysis based on a variational principleIn order to perform numerical analysis, the solids need to be discretized into small elements so that no assumption concerning the roughness distribution is required. BEM employs a different discretization scheme from finite difference method and finite elem...

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Section: Transient Analysis Of Sliding Contactmentioning

confidence: 99%

Transient analysis of sliding contact of layered elastic/plastic solids with rough surfaces

Peng

Bhushan

2003

Microsystem Technologies

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“…The prediction of LPS using mixing enthalpy ( Figure 1 ), thermodynamic calculation ( Figure 2 , Figure 3 b and Table 1 ), and predicted ground state diagram ( Figure 3 a), and experimental observation of the difference in the morphology of Ag between the arc-melted ingots ( Figure 4 , Figure 5 and Figure 6 , and Table 2 ), and rapidly solidified melt-spun ribbons ( Figure 7 , Figure 8 , Figure 9 and Figure 10 , and Table 3 ) offer a unique opportunity for designing composites with Ag globules dispersed in Ti-based metal matrix in Ti-Ag-based alloys. The dispersion of fine globules was reported to be effective for the strengthening of Ti-rare earth-based alloys [ 1 , 2 , 3 , 4 , 5 , 6 ]. The fine Ag dispersion may be effective for increasing the mechanical strength.…”

Section: Discussionmentioning

confidence: 99%

“…Past research focusing on LPS in Ti-based alloys can be summarized based on the following three categories. (1) Ti-rare earth-based alloys for the development of Ti-based alloys with fine globules, focusing on structural materials [1][2][3][4][5][6]. A number of binary Ti-rare earth alloy systems show a monolicic phase diagram with a liquid miscibility gap.…”

Section: Introductionmentioning

confidence: 99%

“…In Ti-rare earth-based alloys (1), many binary alloy systems of Ti–Y [ 11 ], Ti–La [ 3 , 12 ], Ti–Ce [ 13 ], Ti–Pr [ 14 ], Ti–Nd [ 15 ], Ti–Gd [ 16 ], Ti–Dy [ 17 ], and Ti–Yb [ 18 ] exhibit a monolicic phase diagram with a liquid miscibility gap in the phase diagram. Although the flat liquidus implies a metastable liquid miscibility gap in the Ti–Er alloy system, the occurrence of LPS in the Ti–Er alloy system with a flat liquidus line cannot be detected because of the formation of nonmetallic Er globules and Er 2 O 3 oxide globules [ 6 ]. Focusing on the solidification microstructure of the Ti-rare earth-based immiscible alloys with LPS, fine metallic and/or oxide globules with dispersed microstructures have been observed [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

“…Although the flat liquidus implies a metastable liquid miscibility gap in the Ti–Er alloy system, the occurrence of LPS in the Ti–Er alloy system with a flat liquidus line cannot be detected because of the formation of nonmetallic Er globules and Er 2 O 3 oxide globules [ 6 ]. Focusing on the solidification microstructure of the Ti-rare earth-based immiscible alloys with LPS, fine metallic and/or oxide globules with dispersed microstructures have been observed [ 1 , 2 , 3 , 4 , 5 , 6 ]. The formation of fine globules, including the formation of metallic and/or oxide globules, was explained using the liquid miscibility gap and low solubility of rare-earth elements in Ti phase in the thermal equilibrium phase diagrams, and high oxidation tendency of rare-earth elements, among other causes.…”

Section: Introductionmentioning

confidence: 99%

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Alloy Design, Thermodynamics, and Electron Microscopy of Ternary Ti-Ag-Nb Alloy with Liquid Phase Separation

Nagase

2020

Materials

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The Ti–Ag alloy system is an important constituent of dental casting materials and metallic biomaterials with antibacterial functions. The binary Ti–Ag alloy system is characterized by flat liquidus lines with metastable liquid miscibility gaps in the phase diagram. The ternary Ti–Ag-based alloys with liquid phase separation (LPS) were designed based on the mixing enthalpy parameters, thermodynamic calculations using FactSage and Scientific Group Thermodata Europe (SGTE) database, and the predicted ground state diagrams constructed by the Materials Project. The LPS behavior in the ternary Ti–Ag–Nb alloy was investigated using the solidification microstructure analysis in arc-melted ingots and rapidly solidified melt-spun ribbons via trans-scale observations, combined with optical microscopy (OM), scanning electron microscopy (SEM) including electron probe micro analysis (EPMA), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). The solidification microstructures depended on the solidification processing in ternary Ti–Ag–Nb alloys; macroscopic phase-separated structures were observed in the arc-melted ingots, whereas fine Ag globules embedded in the Ti-based matrix were observed in the melt-spun ribbons.

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Microstructure and Properties of a Three-Layer Nuclear Fuel Cladding Prototype Containing Erbium as a Neutronic Burnable Poison

Brachet

Olier

Vandenberghe

et al. 2014

Zirconium in the Nuclear Industry: 17th Volume

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International audienceTo increase cycle length and/or fuel burnup, several theoretical and experimental studies have been performed at CEA. Among them, prospective neutronic calculations have shown that the addition of a few weight percents of erbium into the cladding materials could be a promising alternative to the introduction of the neutronic poison directly into the nuclear fuel pellets. Thus, fabrication of homogeneous Zr-Er alloys has been assessed, at least up to 10 wt. % of erbium and, based on the as-received mechanical properties, an optimum erbium concentration ranging from 3 to 6 wt. % has been derived. However, because of the high-oxygen thermodynamic affinity of erbium, thermal treatments have to be controlled during the fabrication route to limit Er2O3 precipitation and coarsening, which may have detrimental effects on the ductility/toughness of Zr-Er alloys. In parallel, to get more fundamental insights into the underlying phase diagrams, thermodynamic studies have been devoted to experimental assessment and modeling of the Zr-Er-(H-O) system. Because of the detrimental influence of erbium on the corrosion resistance, a three-layer sandwich clad prototype has been developed using corrosion-resistant inner/outer Zr-1Nb layers to protect the intermediate Zr-Er layer from direct water exposure. Compared to a reference Zr-1Nb(O) alloy that has been subjected to the same fabrication route, the three-layer clad prototype shows limited decrease in ductility because of pre-hydriding or after high-temperature steam oxidation e.g., in the case of a loss-of-coolant accident). Moreover, the studies performed so far have shown a spectacular hydride trapping capacity of the intermediate Zr-Er layer both for hydrogen coming from nominal outer corrosion or because of massive secondary hydriding in case of the direct access of water to the Zr-Er intermediate layer. Using μ-ERDA (elastic recoil detection analysis) measurements, detailed studies of the hydrogen spatial redistribution upon thermal cycling has been done. A simple model has been successfully used to characterize the cooling rate influence on the through-wall clad thickness partitioning of hydrogen/hydrides between the three layers, after cooling from a temperature corresponding to full dissolution of hydride

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Interphase boundary precipitation in a Ti-1.7 at. pct Er alloy

Cited by 5 publications

References 27 publications

Transient analysis of sliding contact of layered elastic/plastic solids with rough surfaces

Transient analysis of sliding contact of layered elastic/plastic solids with rough surfaces

Alloy Design, Thermodynamics, and Electron Microscopy of Ternary Ti-Ag-Nb Alloy with Liquid Phase Separation

Microstructure and Properties of a Three-Layer Nuclear Fuel Cladding Prototype Containing Erbium as a Neutronic Burnable Poison

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