Microstructure and mechanical properties of the as-cast and warm rolled Mg-9Li-x(Al-Si)-yTi alloys with x = 1, 3, 5 and y = 0.05 wt.%

Kim, Jeong-Tae; Jeong, Hae Joon; Moon, Yeabin; Kim, Ki Buem; Son, Hyeon-Taek; Jeon, Changwoo; Sim, Jae Won; Moon, Su-Dong; Park, Jin Man

doi:10.1016/j.jallcom.2017.03.349

Cited by 21 publications

(9 citation statements)

References 21 publications

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“…Refractory metal intermetallic composites (RMICs) are considered to be potential replacements for Ni-based superalloys in future aero-engines owing to their higher solidus temperatures compared with Ni, and their promise of meeting property goals [1][2][3]. Nb-silicide-based alloys (also known as Nb-silicide in situ composites, Nb-silicide-based composites, or Nb in situ composites) can be cast and can offer low densities with outstanding balance of mechanical properties at temperatures between 1000 and 1400 • C coupled with oxidation resistance [1,[4][5][6][7]. The latter was improved significantly to meet industry requirements for oxidation behavior at intermediate and high temperatures [2,3,8].…”

Section: Introductionmentioning

confidence: 99%

On the Microstructure and Isothermal Oxidation at 800 and 1200 °C of the Nb-24Ti-18Si-5Al-5Cr-5Ge-5Sn (at.%) Silicide-Based Alloy

Hernández-Negrete

Tsakiropoulos

2020

Materials

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The research presented in this paper aspired to understand how the simultaneous addition of Ge and Sn in an Hf-free Nb-silicide-based alloy affected its oxidation resistance. Results are presented for the Nb-24Ti-18Si-5Al-5Cr-5Ge-5Sn alloy (at.%) which was studied in the as-cast and heat-treated (1400 °C/100 h) conditions and after isothermal oxidation in air at 800 and 1200 °C. There was macrosegregation in the cast alloy, in which the Nbss formed at a low volume fraction and was not stable after heat treatment at 1400 °C. The βNb5Si3, A15-Nb3Sn, and C14-NbCr2 were stable phases. The alloy did not undergo pest oxidation at 800 °C, and there was no spallation of its scale at 1200 °C. There was enrichment in Ge and Sn in the substrate below the scale/substrate interface, where the compounds Nb3Sn, Nb5Sn2Si, (Ti,Nb)6Sn5, and Nb5Ge3 were formed. After the oxidation at 1200 °C, the solid solution in the bulk of the alloy was very Ti-rich (Ti,Nb)ss. Improvement of oxidation resistance at both temperatures was accompanied by a decrease and increase, respectively, of the alloy parameters VEC (valence electron concentration) and δ, in agreement with the alloy design methodology NICE (Niobium Intermetallic Composite Elaboration). The elimination of scale spallation at 1200 °C was attributed (a) to the formation of Ti-rich (Ti,Nb)ss solid solution and (Ti,Nb)6Sn5, respectively, in the bulk and below the scale, (b) to the low concentration of Cr in the scale, (c) to the absence of GeO2 in the scale, (d) to the formation of αAl2O3 in the scale, and (e) to the presence (i) of Nb5Ge3 below the scale/substrate interface and (ii) of oxides in the scale, namely, SiO2, Al2O3, TiO2, and SnO2, and Ti2Nb10O29,TiNb2O7, and AlNbO4, respectively, with a range of intrinsic thermal shock resistances and coefficient of thermal expansion (CTE) values that reduced stresses in the scale and the substrate below it.

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Section: Introductionmentioning

confidence: 99%

On the Microstructure and Isothermal Oxidation at 800 and 1200 °C of the Nb-24Ti-18Si-5Al-5Cr-5Ge-5Sn (at.%) Silicide-Based Alloy

Hernández-Negrete

Tsakiropoulos

2020

Materials

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“…The modified sealed-plug, as shown in the sketch of hexagonal anvil apparatus ( Figure S1), was used to avoid melting leakage. Samples are designated as follows: a Mg−8Li alloy with high 24 extrusion, 25−27 ECAP, 28,29 and aging. 30,31 (d) Comparison of specific yield strength between UHP Mg−8Li alloy and typical commercial Mg alloys.…”

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confidence: 99%

Achieving High Strength and Ductility in Magnesium Alloys via Densely Hierarchical Double Contraction Nanotwins

Xin

et al. 2017

Nano Lett.

123

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Light-weight magnesium alloys with high strength are especially desirable for the applications in transportation, aerospace, electronic components, and implants owing to their high stiffness, abundant raw materials, and environmental friendliness. Unfortunately, conventional strengthening methods mainly involve the formation of internal defects, in which particles and grain boundaries prohibit dislocation motion as well as compromise ductility invariably. Herein, we report a novel strategy for simultaneously achieving high specific yield strength (∼160 kN m kg) and good elongation (∼23.6%) in a duplex magnesium alloy containing 8 wt % lithium at room temperature, based on the introduction of densely hierarchical {101̅1}-{101̅1} double contraction nanotwins (DCTWs) and full-coherent hexagonal close-packed (hcp) particles in twin boundaries by ultrahigh pressure technique. These hierarchical nanoscaled DCTWs with stable interface characteristics not only bestow a large fraction of twin interface but also form interlaced continuous grids, hindering possible dislocation motions. Meanwhile, orderly aggregated particles offer supplemental pinning effect for overcoming latent softening roles of twin interface movement and detwinning process. The processes lead to a concomitant but unusual situation where double contraction twinning strengthens rather than weakens magnesium alloys. Those cutting-edge results provide underlying insights toward designing alternative and more innovative hcp-type structural materials with superior mechanical properties.

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“…Numerous attempts have been made to get an excellent balance of strength and ductility of commercial wrought Mg alloys. Grain refinement and precipitation hardening, especially texture modification, have been proved to be effective methods for enhancing the mechanical properties of wrought Mg alloys [8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Study on Bulk Texture and Mechanical Properties of As-Extruded Wide Mg-Al-Zn Alloy Sheets with Different Al Addition

Zha

et al. 2022

Materials

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The wide Mg alloy sheets produced by hot extrusion usually can easily form an inhomogeneous texture, resulting in anisotropic mechanical properties and poor formability. However, few studies have been carried out on the bulk texture investigation at different areas of as-extruded Mg alloy sheets, especially the Mg alloys with different alloying elements. In this work, the effect of Al on the bulk texture and mechanical properties at different areas for three wide Mg-Al-Zn alloy sheets with different Al contents (Mg-3Al-0.5Zn, Mg-8Al-0.5Zn and Mg-9Al-0.5Zn) are mainly investigated by neutron diffraction. The results showed that a strong and uneven basal texture was formed in the Mg-3Al-0.5Zn sheet. Meanwhile, the intensity of the basal texture was significantly weakened due to the numerous fine precipitates of Mg17Al12 particles, with the Al content increasing, which hinder the grain growth during extrusion, while fine recrystallized grains have a more random orientation. The enhanced tensile properties in Mg-8Al-0.5Zn and Mg-9Al-0.5Zn alloy sheets are ascribed to the cooperation effect of a refined microstructure, precipitates and weakened basal texture. Among the three Mg alloy sheets, the Mg-8Al-0.5Zn alloy sheet has a yield strength of about 270 MPa, an ultimate tensile strength of about 330 MPa and ultimate elongation of about 16% in the extrusion direction, which possesses the most excellent comprehensive mechanical properties.

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Microstructure and mechanical properties of the as-cast and warm rolled Mg-9Li-x(Al-Si)-yTi alloys with x = 1, 3, 5 and y = 0.05 wt.%

Cited by 21 publications

References 21 publications

On the Microstructure and Isothermal Oxidation at 800 and 1200 °C of the Nb-24Ti-18Si-5Al-5Cr-5Ge-5Sn (at.%) Silicide-Based Alloy

On the Microstructure and Isothermal Oxidation at 800 and 1200 °C of the Nb-24Ti-18Si-5Al-5Cr-5Ge-5Sn (at.%) Silicide-Based Alloy

Achieving High Strength and Ductility in Magnesium Alloys via Densely Hierarchical Double Contraction Nanotwins

Study on Bulk Texture and Mechanical Properties of As-Extruded Wide Mg-Al-Zn Alloy Sheets with Different Al Addition

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