首页期刊导航|Intermetallics
期刊信息/Journal information
Intermetallics
Elsevier Science
Intermetallics

Elsevier Science

0966-9795

Intermetallics/Journal IntermetallicsSCIISTPEI
正式出版
收录年代

    Microstructure and properties of CoCrNiFeMnAl0.5 high-entropy alloys prepared by gas atomization combined with oscillatory pressure sintering

    Tong Y.Ren Z.Hu Y.Ji X....
    9页
    查看更多>>摘要：? 2022 Elsevier LtdIn order to improve the mechanical strength of Cantor alloy and obtain the uniform microstructure, about 9.1 at.% of Al element was introduced and a new CoCrNiFeMnAl0.5 HEAs was prepared by gas atomization combined with oscillatory pressure sintering. The effects of powder sizes on the microstructure and mechanical properties of the as-sintered alloys were investigated and the corresponding strengthening mechanism was discussed. The results show that the CoCrNiFeMnAl0.5 HEAs were composed of FCC phase with good plasticity and BCC phase with high strength. The as-sintered alloys have higher relative density and uniform microstructure without the defects of composition segregation and coarse structure like the as-cast alloy. The yield strength and microhardness of the as-sintered alloys increased to 775 MPa and 369.3 HV, which were 173% and 104% higher than that of the as-cast alloy, respectively. It is indicated that the strength and microhardness of the as-sintered alloys depend on the powder sizes. The strengthening mechanisms of the as-sintered alloys were mainly attributed to the second phase strengthening and the grain boundary strengthening.
      原文链接:
    • NSTL
    • Elsevier

    Mechanical response of as-cast equiatomic high entropy alloy CuFeCoNiMn

    Bibhanshu N.Prasad N.Avadhani G.S.Suwas S....
    8页
    查看更多>>摘要：? 2022 Elsevier LtdThe mechanical behavior of a cast CuMnNiFeCo high entropy alloy, with larger grains and 0.5% (by volume) of micro-porosities, was investigated at room temperature under a unidirectional tensile load. The initial microstructural features show two types of the Face Centered Cubic (FCC) structure (FCC-1 and FCC-2), corresponding to the dendritic arms, in the as-cast alloy, exhibiting two different contrasts. FCC-1 shows the presence of the elements, Cu, Mn, and Ni; while FCC-2 contains, Fe, Co, and Ni. The cast alloy, in spite of the large grain size and a significant fraction of micro-porosities, shows high strength along with good ductility. The response of the cast alloy, under tensile deformation, was examined from the engineering stress-strain and true stress-strain plots. The hardening curve, derived from the true stress-strain plot, shows three parts, as a function of the true stress (and hence, true strain). Microstructural investigations indicate that the formation and growth of deformation twins, which restrict dislocation mobility, could be behind the hardening response. The stress (strain) levels on both sides of the intermediate level undergo dislocation-dominated deformation. It appears that elemental segregation may provide respite from early failure starting from the micro-porosities. In fact, Cu – rich regions have been observed to behave like a flow line, connecting one micro-porosity with another, thereby preventing them from opening up under the deformation load.
      原文链接:
    • NSTL
    • Elsevier

    Microstructure and texture development in CoCrNi medium entropy alloy processed by severe warm cross-rolling and annealing

    Saha J.Bhattacharjee P.P.Saha R.
    12页
    查看更多>>摘要：? 2022 Elsevier LtdThe effect of cross-rolling on microstructure and texture evolution in equiatomic CoCrNi medium entropy alloy (MEA) was investigated in the present work. For this purpose, the MEA was warm-rolled to 90% reduction in thickness at 400 °C by unidirectional and different cross-rolling routes. The heavily deformed specimens were further annealed at temperatures varying from 700 °C to 1200 °C. The development of fine-scale microstructures and profuse shear band formation was confirmed in all the processed materials. Compared to unidirectional processed material, the different cross-rolled materials showed greater propensity for forming intersecting shear bands. Higher hardness in the different cross-rolled materials was consistent with finer microstructure and abundant shear bands. Unidirectional processed material showed weak brass ({110}<112>) component, whereas the different cross-rolled material showed rotated brass components. Upon annealing, the different cross-rolled materials showed smaller grain sizes than the unidirectional processed material due to more abundant potential nucleation sites. The recrystallization texture of the different processed materials showed retention of the deformation texture components. High fractions of random components indicated weak recrystallization texture, contributed by the absence of preferential nucleation and growth and profuse annealing twin formation.
      原文链接:
    • NSTL
    • Elsevier

    Effect of pre-heating and post-weld heat treatment on structure and mechanical properties of laser beam-welded Ti2AlNb-based joints

    Dinse R.Riekehr S.Nochovnaya N.Alekseev E....
    11页
    查看更多>>摘要：? 2022The effect of pre-heating and post-weld heat treatment on microstructure and mechanical properties of laser-welded joints in a Ti–23Al–23Nb-1.4V-0.8Zr-0.4Mo-0.4Si (at.%) alloy was studied. Laser beam-welding was carried out at room temperature as well as after pre-heating up to 800°С. The post-weld heat treatment comprised either air quenching from 920°С followed by aging at 800°С or only aging at 800°С. The microstructure of the fusion zone consisted of columnar β-grains after welding at room temperature and 400 °C or both the columnar and large equiaxed crystals at 600 and 800 °C. An increase in the pre-heating temperature caused the columnar β-crystals growth as well as an increase in the fusion zone and heat-affected zone widths. Meanwhile, a decrease in the Al and Ti content, as well as an increase in both the porosity and gaseous elements content (O and N) after welding at 600–800 °C were found. The microhardness of each joint obtained after welding with pre-heating temperatures up to 600 °C was lower than that of the base material. All the welded joints showed the yield strength and ultimate tensile strength levels between 1070 and 1110 MPa, which correspond to approximately 80% of the base metal level. Reasonable total elongation of the joint was achieved after welding at 400 °C (4.3%). The post-weld heat treatment involving air quenching from 920 °C with subsequent aging at 800 °C for 6 h demonstrated the best results. The heat treatment resulted in the precipitation of the O- and α2-phases and an increase in total elongation to 6.5%.
      原文链接:
    • NSTL
    • Elsevier

    Effects of sintering temperature and Y2O3/Ti addition on microstructure and hardness of ODS-AlCrFeNi HEAs

    Peng S.Hou J.Yu L.Lu Z....
    12页
    查看更多>>摘要：? 2022 Elsevier LtdOxide dispersion strengthened (ODS) alloys are leading candidate structural materials for advanced nuclear reactor application due to their excellent high strength and radiation tolerance. In this paper, ODS AlCrFeNi high entropy alloys (HEAs) were synthesized via mechanical alloying (MA) and spark plasma sintering (SPS) to study the effects of sintering temperature (from 1050 °C to 1250 °C) and different Y2O3/Ti addition amounts on the microstructure and hardness. The microstructure was characterized by XRD, SEM, EBSD and HRTEM, and the micro-hardness was tested. The results demonstrated that after MA and SPS, spinodal decomposition occurs in the matrix, in which Fe/Cr enriched disordered BCC phase and Ni/Al enriched ordered B2 phase are formed. At the higher sintering temperature (1250 °C), additional FCC phase appears in 0.3 YT, which is contributed to the formation of higher volume fraction of Al2O3 at powder/grain boundaries so that spinodal decomposition is partly suppressed. At the lower sintering temperature (1100 °C), FCC phase could be formed when Y2O3+Ti amount is lower (0.6 wt%, 1.0 wt%). The hardness of ODS-AlCrFeNi is notably improved when Y2O3 and Ti are added in the same weight percent which is up to 1 wt% or above. The average grain size of 3.0 YT alloy (3 wt% Y2O3+3 wt% Ti) is the smallest, which is 240 nm. The average size of precipitates in 3.0 YT alloy is 8.7 nm, while the number density is the highest (3.3 × 1022/m3). The addition of Y2O3/Ti can modify the types of nanoscale oxides in the ODS-AlCrFeNi. The precipitates in 0Y alloy (without Y2O3 and Ti addition) are Al-rich oxides, while the precipitates observed in 3.0 YT alloy include AlYO3, Al2Y4O9, Y2TiO5, YTiO3, Al2TiO5 and Al2O3. The grain boundary strengthening and precipitation strengthening are dominated in 3.0 YT alloy leading to the highest hardness increment compared with 0Y alloy and the hardness of 3.0 YT alloy reaches 751 HV.
      原文链接:
    • NSTL
    • Elsevier

    Effect of thermomechanical treatment on the microstructure evolution and mechanical properties of lightweight Ti65(AlCrNb)35 medium-entropy alloy

    Liao Y.C.Jang J.S.C.Chen P.S.Tsai P.H....
    7页
    查看更多>>摘要：? 2022 Elsevier LtdLightweight Ti65(AlCrNb)35 medium-entropy alloy (Ti-65) ingots were produced through arc melting and drop casting in a water-cooled copper mold. These alloy ingots were then treated through a sequence of homogenization, hot rolling, cold rolling, and recrystallization. The effect of this thermomechanical treatment (TMT) on their microstructures and mechanical properties was investigated through X-ray diffraction (XRD), electron backscatter diffraction analysis through scanning electron microscopy, and mechanical testing. The XRD results demonstrated that the Ti-65 alloy maintained a body-centered cubic structure after 50% hot rolling, 70% cold rolling, and recrystallization at 900 °C, 1000 °C, and 1100 °C, respectively. The fully recrystallized sample had an 80% smaller grain size than the as-cast sample. The cold-rolled Ti-65 alloy specimen exhibited a high tensile strength of 1620 MPa. In comparison with the tensile strength of the as-cast Ti-65 sample (1100 MPa), that of the Ti-65 alloy following annealing and subsequent partial recrystallization was significantly increased (1380 MPa). This tensile strength enhancement is attributable to its heterostructure composition of deformed bands and smaller recrystallized grains. This study demonstrated that an effective strength–ductility synergy of the Ti-65 alloy can be achieved through various TMTs.
      原文链接:
    • NSTL
    • Elsevier

    4D synchrotron X-ray tomographic study of the influence of transverse magnetic field on iron intermetallic compounds precipitation behavior during solidification of Al–Si–Fe alloy

    Cao J.Shuai S.Huang C.Hu T....
    11页
    查看更多>>摘要：? 2022 Elsevier LtdHard and brittle iron intermetallic compounds (IMCs) will be formed during solidification due to the existence of iron element in Aluminum alloy. These IMCs will cause cracks or fractures in the material, which can deteriorate the mechanical properties. Synchrotron X-ray tomography were used to study the real time formation and growth dynamics of IMCs in Al-10 wt.%Si-1 wt.%Fe alloy during solidification under transverse magnetic field (TMF). The results indicated that the precipitation behavior of IMCs was significantly affected by 0.07 T TMF. The IMCs were observed to form only on the periphery of the sample under TMF, comparing with random distribution without TMF. In addition, the growth dynamics of IMCs were also affected by TMF. When solidified without TMF, an explosive nucleation and growth of IMCs was presented at the intermediate solidification stage, where a large number of fine IMCs precipitated at the entire regions of the sample. In contrast, the IMCs located at the periphery areas were observed to grow steadily under TMF. The growth rate and formation mechanism of IMCs were also quantified and revealed, showing difference with and without TMF. The tip growth rate was relatively stable when solidified with TMF, while an accelerating growth stage was presented when TMF is absent. The discrepancy in precipitation behavior of IMCs could be best explained as the convection of the melt resulted from the applied TMF. The TMF was demonstrated to generate a directional flow with a velocity of ～3.3 mm/s. The flow was supposed to drive the Fe solute from the center to the edge of the sample, providing enough Fe solute for IMCs to nucleate and grow on the surface of the sample. In addition, due to the influence of TMF induced flow on the distribution of Fe solute and temperature, the morphology and tip growth rate of IMCs were also affected. The result presented in current study provides the possibility to regulate the precipitation behavior of Fe-rich IMCs in Al alloys. The imposed TMF also shows the potential application in Fe removal by driving the Fe solute to the surface of sample in Al alloys.
      原文链接:
    • NSTL
    • Elsevier

    Effects of V content on the microstructure and mechanical properties of Nb31Ti37-xZr26Al6Vx refractory medium-entropy alloys

    Huang R.Lu Y.P.Li W.Li C.J....
    10页
    查看更多>>摘要：? 2022 Elsevier LtdMost refractory complex concentrated alloys (CCAs) exhibit limited plasticity and high density, which greatly limits their large-scale applications. To address these issues, a series of Nb31Ti37-xZr26Al6Vx (x = 3, 5, 7, 9, and 11 at. %) refractory medium-entropy alloys (RMEAs) were designed and prepared in this work with the help of phase diagram calculation software. The synergistic effects of V and Ti on the microstructure, mechanical properties, and strengthening mechanisms of Nb31Ti37-xZr26Al6Vx RMEAs are investigated in detail. Compared with the reported CCAs with limited plasticity and high density, our alloys with a single BCC structure offer excellent compressive plasticity greater than 50% at room temperature and a lower density less than 6.4 g/cm3. Alloys have higher yield strength at room temperature with the increasing content of V. The high yield strength of alloys primarily originates from the inherent yield strength of the alloy's components and the solution strengthening resulting from the lattice distortion. The alloys studied in this work provide evidence that the high-strength RMEAs with excellent plasticity can be obtained through careful composition design.
      原文链接:
    • NSTL
    • Elsevier

    Thermally induced microstructure evolution and effects on the corrosion behaviors of AlFeSi metallic glass coatings

    Ge Y.Cheng J.Yan C.Xue L....
    11页
    查看更多>>摘要：? 2022 Elsevier LtdThe effects of the devitrification process on the microstructure evolution and corrosion resistance of arc-sprayed AlFeSi metallic glass coatings were explored. Detailed characterizations revealed that the structural relaxation coating (annealing at 300 °C) retains the phase structures of the as-sprayed coating. Annealing at 350 °C (above the onset crystallization temperature) facilitates nanoscale Al9Fe2Si2 and Al9FeSi3 new phase precipitation. Annealing at over 400 °C (above the full crystallization temperature) induces completely crystallized structures of α-Al, Al9Fe2Si2, and Al9FeSi3 in the coatings. The crystalline size response of the coatings depends on the annealing temperatures. Electrochemical tests indicated that devitrification increases the current density and reduces the impedance of the coatings. The best corrosion resistance is discernible for the as-sprayed AlFeSi metallic glass coating. The decreased amorphous fraction, larger nanocrystals, and crystal structure heterogeneity in the as-annealed coatings are responsible for the degradation of corrosion resistance. Additionally, the variations in the compositions and natures of the passive films with thermally induced microstructure evolution were elucidated in detail.
      原文链接:
    • NSTL
    • Elsevier

    Magnetic and electronic properties of the RECu4Al8 (RE = Tb, Dy, Ho, and Er) intermetallic compounds

    Mercena S.G.Melo A.T.Lima A.F.
    7页
    查看更多>>摘要：? 2022 Elsevier LtdSpin density functional theory calculations were employed to study some of the magnetic and electronic properties of the RECu4Al8 (RE = Tb, Dy, Ho, and Er) intermetallic compounds in their tetragonal crystal structure and their collinear antiferromagnetic state. The exchange and correlation electronic effects were treated by both a generalized gradient approximation (GGA) in its recently revised version for solids (GGA-PBEsol), and the addition of the effective Hubbard U term (GGA-PBEsol + Ueff) in the RE 4f states. Based on these methodologies, the total magnetic moment of the RE atoms and their spin and orbital contributions were determined. The total magnetic moment calculated with GGA + PBEsol (Ueff = 0.0 eV) agreed with the experimental data, except for the TbCu4Al8 system, in which the addition of the Ueff term was needed for a better description. Using GGA + PBEsol, the magnetocrystalline anisotropy energy (MAE), easiest magnetization axis (EMA), exchange splitting of the RE 4f states (Δex), and the electronic specific heat coefficients (γ) of the four compounds were determined. The values of the MAE found for TbCu4Al8, DyCu4Al8, HoCu4Al8, and ErCu4Al8 were 3.13, 9.11, 26.93, and 17.41 meV/f.u., respectively. The EMA for TbCu4Al8, DyCu4Al8, and HoCu4Al8 was found to be [111], while for ErCu4Al8 it was [001]. The values of Δex were equal to 4.3, 3.6, 2.8, and 1.9 eV for TbCu4Al8, DyCu4Al8, HoCu4Al8, and ErCu4Al8, respectively.
      原文链接:
    • NSTL
    • Elsevier