Creep behaviour of hot isostatically pressed niobium alloy powder compacts

Wadsworth, J.; Roberts, Craig; Rennhack, E. H.

doi:10.1007/bf00543885

Cited by 22 publications

(6 citation statements)

References 4 publications

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“…In Figure 7 C there are two sets of data for the solid solution alloy Nb-5.4Hf-2Ti [ 113 ], which, as indicated in the caption, correspond to two different activation energies in έ = A(σ/E) n exp(−Q/RT), where E is the Young’s modulus [ 114 ]. The higher activation energy is closer to the activation energy for the diffusion of Hf in Nb [ 6 ].…”

Section: Objectives Results and Discussionmentioning

confidence: 99%

On Nb Silicide Based Alloys: Alloy Design and Selection

Tsakiropoulos

2018

Materials

369

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The development of Nb-silicide based alloys is frustrated by the lack of composition-process-microstructure-property data for the new alloys, and by the shortage of and/or disagreement between thermodynamic data for key binary and ternary systems that are essential for designing (selecting) alloys to meet property goals. Recent publications have discussed the importance of the parameters δ (related to atomic size), Δχ (related to electronegativity) and valence electron concentration (VEC) (number of valence electrons per atom filled into the valence band) for the alloying behavior of Nb-silicide based alloys (J Alloys Compd 748 (2018) 569), their solid solutions (J Alloys Compd 708 (2017) 961), the tetragonal Nb5Si3 (Materials 11 (2018) 69), and hexagonal C14-NbCr2 and cubic A15-Nb3X phases (Materials 11 (2018) 395) and eutectics with Nbss and Nb5Si3 (Materials 11 (2018) 592). The parameter values were calculated using actual compositions for alloys, their phases and eutectics. This paper is about the relationships that exist between the alloy parameters δ, Δχ and VEC, and creep rate and isothermal oxidation (weight gain) and the concentrations of solute elements in the alloys. Different approaches to alloy design (selection) that use property goals and these relationships for Nb-silicide based alloys are discussed and examples of selected alloy compositions and their predicted properties are given. The alloy design methodology, which has been called NICE (Niobium Intermetallic Composite Elaboration), enables one to design (select) new alloys and to predict their creep and oxidation properties and the macrosegregation of Si in cast alloys.

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Section: Objectives Results and Discussionmentioning

confidence: 99%

On Nb Silicide Based Alloys: Alloy Design and Selection

Tsakiropoulos

2018

Materials

369

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“…In 1982, Wadsworth et al [21] fabricated a commercial C103 niobium alloy (Ni + 10 wt.% Hf + 1 wt.% Ti) by duplex hipping process for high-performance missile and space application systems. The microstructure of the fabricated metal had an average grain size of 75 μm.…”

Section: Coarse-grained Superplasticitymentioning

confidence: 99%

Effect of Grain Size on Superplastic Deformation of Metallic Materials

Raja¹,

Jayaganthan²,

Tiwari³

et al. 2020

Aluminium Alloys and Composites

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The superplastic deformation exhibited by metals with different grain sizes and their corresponding deformation mechanism influences the industrial metalforming processes. The coarse-grained materials, which contain grain size greater than 20 μm, exhibited superplastic deformation at high homologous temperature and low strain rate of the order of 10 −4 s −1. Fine grain materials (1-20 μm) are generally considered as favorable for superplastic deformation. They possess highstrain-rate sensitivity "m" value, approximately, equal to 0.5 at the temperature of 0.5 times the melting point and at a strain rate of 10 −3 to 10 −4 s −1. Ultrafine grains (100 nm to less than 1 μm) exhibit superplasticity at high strain rate as well as at low temperature when compared to fine grain materials. It is attributed to the fact that both temperature and strain rates are inversely proportional to the grain size in Arrhenius-type superplastic constitute equation. The superplastic phenomenon with nano-sized grains (10 nm to less than 100 nm) is quite different from their higher-scale counterparts. It exhibits high ductility with high strength. Materials with mixed grain size distribution (bimodal or layered) are found to exhibit superior superplasticity when compared to the homogeneous grain-sized material. The deformation mechanisms governing these superplastic deformations with different scale grain size microstructures are discussed in this chapter.

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“… Superplastic behaviors of the HC‐LRMEA samples. a) engineering stress‐strain curves obtained under tensile loading at temperatures of 973, 1073, and 1173 K and strain rates of 10 −3 and 10 −2 s −1 ; b) images of representative specimens fractured under temperatures of 973, 1073, and 1173 K and a strain rate of 10 −2 s −1 ; c) stress–strain, σ–ε , curves and strain‐rate sensitivity ( m ) values obtained from strain‐rate jump tests conducted at 1173 K with 4 different strain rates of 5 × 10 −4 , 1 × 10 −3 , 5 × 10 −3 , and 1 × 10 −2 s −1 , where n = 1/ m is the stress exponent; d) the hardness distribution of the sample after coarse‐grained superplastic deformation; the inset in (d) illustrates the hardness test and morphology of hardness indentation; e) yield strength versus superplastic elongation at high strain rates (10 −2 s −1 ) of coarse‐grained superplastic magnesium alloys, [ 25 , 26 , 58 , 59 , 60 , 61 , 62 ] coarse‐grained superplastic aluminum alloys, [ 28 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ] coarse‐grained niobium alloy, [ 73 ] coarse‐grained superplastic intermetallics, [ 74 , 75 , 76 ] and coarse‐grained superplastic titanium alloys. [ 9 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 ] …”

Section: Resultsmentioning

confidence: 99%

“…By converting this hardness to the strength, a formula of HV ≈3 σ y [ 55 ] is used to characterize the strength, which indicates that the strength of HC‐LRMEA is still higher than 1 GPa after superplastic deformation (Figure 2d ). In addition, HC‐LRMEA is compared with other coarse‐grained superplastic alloys, including coarse‐grained superplastic magnesium alloys, [ 26 , 27 , 56 , 57 , 58 , 59 , 60 ] coarse‐grained superplastic aluminum alloys, [ 29 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ] coarse‐grained niobium alloy, [ 71 ] coarse‐grained superplastic intermetallics, [ 72 , 73 , 74 ] and coarse‐grained superplastic titanium alloys, [ 9 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 ] Superplastic elongation at high strain rates (≥10 −2 s −1 ) versus strength is plotted in Figure 2e . The strength values of the coarse‐grained superplastic magnesium and aluminum alloys are relatively low, making them difficult to use in some high‐strength conditions.…”

Section: Resultsmentioning

confidence: 99%

Efficient Coarse‐Grained Superplasticity of a Gigapascal Lightweight Refractory Medium Entropy Alloy

Jia

et al. 2023

Advanced Science

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Superplastic metals that exhibit exceptional ductility (>300%) are appealing for use in high‐quality engineering components with complex shapes. However, the wide application of most superplastic alloys has been constrained due to their poor strength, the relatively long superplastic deformation period, and the complex and high‐cost grain refinement processes. Here these issues are addressed by the coarse‐grained superplasticity of high‐strength lightweight medium entropy alloy (Ti43.3V28Zr14Nb14Mo0.7, at.%) with a microstructure of ultrafine particles embedded in the body‐centered‐cubic matrix. The results demonstrate that the alloy reached a high coarse‐grained superplasticity greater than ≈440% at a high strain rate of 10−2 s−1 at 1173 K and with a gigapascal residual strength. A consecutively triggered deformation mechanism that sequences of dislocation slip, dynamic recrystallization, and grain boundary sliding in such alloy differs from conventional grain‐boundary sliding in fine‐grained materials. The present results open a pathway for highly efficient superplastic forming, broaden superplastic materials to the high‐strength field, and guide the development of new alloys.

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Creep behaviour of hot isostatically pressed niobium alloy powder compacts

Cited by 22 publications

References 4 publications

On Nb Silicide Based Alloys: Alloy Design and Selection

On Nb Silicide Based Alloys: Alloy Design and Selection

Effect of Grain Size on Superplastic Deformation of Metallic Materials

Efficient Coarse‐Grained Superplasticity of a Gigapascal Lightweight Refractory Medium Entropy Alloy

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