Microstructural characterization and quantitative phase analysis of Ni-rich NiTi after stress assisted aging for long times using the Rietveld method

Naji, Hojjat; Khalil‐Allafi, Jafar; Khalili, Vida

doi:10.1016/j.matchemphys.2019.122317

Cited by 25 publications

(9 citation statements)

References 28 publications

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“…It should also be remembered that due to dynamic conditions of the explosive welding process (intense mixing and high cooling rates), it is possible to have phases with compositions deviating from those observed in the equilibrium phase diagram, i.e. metastable phases such as Ti 50 Ni 15 Cu 35 , Ti 4 Ni 3 , Ni 4 Ti 3 , Al 9 Ni 2 , Fe 9.64 Ti 0.36 , TiAl 2 often reported in the literature (Gargarella et al, 2013; Bataev et al, 2015, 2017; Radi et al, 2018; Neiman et al, 2019; Kwiecien et al, 2020; Naji et al, 2020). Microstructural analysis of the examined interface zones was extended to the adhering regions of joined plates by applying EBSD measurements taken from the Ti/Alloy 400 interface area.…”

Section: Resultsmentioning

confidence: 98%

“…Fortunately, TEM can help to solve this problem and the obtained results will be described hereafter. It should also be remembered that due to dynamic conditions of the explosive welding process (intense mixing and high cooling rates), it is et al, 2015Radi et al, 2018;Neiman et al, 2019;Kwiecien et al, 2020;Naji et al, 2020). Microstructural analysis of the examined interface zones was extended to the adhering regions of joined plates by applying EBSD measurements taken…”

Section: Resultsmentioning

confidence: 99%

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A Detailed Interface Characterization of the Explosively Welded Three-Layered Ti Gr 1/Alloy 400/1.4462 Steel Clads Before and After Heat Treatment

et al. 2021

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The presented research focused on the microstructural characteristics of explosively welded three-layered Ti Grade (Gr) 1/Alloy 400/1.4462 steel clads before and after heat treatment being of large practical potential. Scanning electron microscopy (SEM) analyses have shown that both interfaces formed between the plates are continuous and without defects. The in-depth examination was dedicated to the upper Ti Gr 1/Alloy 400 interface, located closer to the explosive material, therefore, subjected to more extreme welding conditions. The presence of cubic phase Ti2Ni, hexagonal phase Ni3Ti, and tetragonal phase (Cu x Ni1−x)2Ti were confirmed within the melted zones, which slightly widened due to annealing, being an essential step in the manufacturing of these modern materials. Transmission electron microscopy observations in the nano scale confirmed the preliminary chemical composition analyses collected with energy-dispersive X-ray spectroscopy in SEM. They additionally revealed the interface zone microstructure transformation due to the annealing. It was evidenced that initially mixed phases in the form of grains, after heat treatment formed irregular bands arranged in the following sequence: Alloy 400/Ni3Ti/(Cu x Ni1−x)2Ti/Ti2Ni/Ti Gr 1. A clear segregation of Cu and Ni forming two separate layers was also noticed. These diffusion phenomena may influence the strength of the final product, therefore need further studies regarding the prolonged annealing state.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

A Detailed Interface Characterization of the Explosively Welded Three-Layered Ti Gr 1/Alloy 400/1.4462 Steel Clads Before and After Heat Treatment

et al. 2021

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“…The volume fraction of retained austenite (RA) is determined through XRD with TOPAS software and Rietveld Method (RM). [ 30–33 ] It can be seen from Figure 10 a that the peak of (220) γ is weak and the volume fraction of RA in the 730‐4 h‐Q and CR‐Q is 1.92% and 2.99%. In this event, all samples are fully martensite because the volume fraction of RA is lower than the XRD detection accuracy (3–5%).…”

Section: Resultsmentioning

confidence: 99%

Microstructure and Mechanical Properties of a Novel Ultra‐High Strength Hot‐Stamped Steel with High Hardenability

Chen

Chu

et al. 2022

steel research int.

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Herein, it is shown that the hot‐stamped steel exhibits high hardenability with a critical cooling rate of about 0.7 °C s−1 due to its unique chemical composition. The microstructure of the annealed sheet consists of ferrite, spherical carbides, and intergranular martensite. Thereinto, the generation of intergranular martensite can eliminate the yield point elongation and reduce the ratio of yield strength to ultimate tensile strength. Furthermore, compared with commercial 30MnB5 steel, the experimental steel (40Mn2CrNbV) quenched sheet shows excellent mechanical properties: yield strength (YS) = 1361 MPa, ultimate tensile strength (UTS) = 2422 MPa, and total elongation (TE) = 6.1%. Additionally, it is found that the Cr7C3 with a mean diameter of 240 ± 50 nm in the annealed quenching sheet can hinder dislocation movement to increase the yield strength. The coherent Nb‐rich (Nb, V)C precipitate (a mean diameter is <50 nm) in the cold‐rolled quenched sheet can improve the mechanical properties of the hot‐stamped steel.

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Section: Introductionmentioning

confidence: 99%

“…Controlling the phase transformation of Ni-rich NiTi SMAs at room temperature is necessary for some of the technologies operating in this range [11][12][13]. However, the presence of metastable intermediate phases (Ni4Ti3, Ni3Ti2) that affect the transformation temperatures in Nirich NiTi alloys are undesirable [11,14]. Researchers are attempting to alloy with a third element to minimize these undesirable phases in Ni-rich NiTi alloys system in a way that does not have a significant effect on phase transformation temperatures [15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Karbon Eklenmiş NiTi Şekil Bellek Alaşımlarının Isı Davranışı ve Mikro Yapısının İncelenmesi

ERCAN

2022

International Journal of Innovative Engineering Applications

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Original scientific paperThis study aims to examine the thermal and microstructural properties of NiTiC1 and NiTiC2 shape memory alloys (SMAs) produced by arc-melting method. It was observed that additive C did not alter the phase transformation order which remained as one-step (𝐵2 ↔ 𝐵19′). Additionally, the effect of C addition on thermal properties of the Ni-riched NiTi alloy(s), including temperature hysteresis, enthalpy, entropy, and Gibbs free energies were also determined. An increase in the amount of C noticeably reduced the detectable grain size and thus decreased the elastic energy of the alloy. In DSC analysis, the presence of martensitic phases in the alloys was determined below the room temperature. The presence of B2 austenite, Ni4Ti3 precipitate, and TiC phases were detected in XRD analyses, which were supported by SEM-EDX results. Grain boundaries were clearly observed and precipitates were found to be homogeneously distributed.

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Microstructural characterization and quantitative phase analysis of Ni-rich NiTi after stress assisted aging for long times using the Rietveld method

Cited by 25 publications

References 28 publications

A Detailed Interface Characterization of the Explosively Welded Three-Layered Ti Gr 1/Alloy 400/1.4462 Steel Clads Before and After Heat Treatment

A Detailed Interface Characterization of the Explosively Welded Three-Layered Ti Gr 1/Alloy 400/1.4462 Steel Clads Before and After Heat Treatment

Microstructure and Mechanical Properties of a Novel Ultra‐High Strength Hot‐Stamped Steel with High Hardenability

Karbon Eklenmiş NiTi Şekil Bellek Alaşımlarının Isı Davranışı ve Mikro Yapısının İncelenmesi

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