The selectivity of hydrogenation of furfural can be tuned to furfuryl alcohol, cyclopentanone, and cyclopentanol by tuning the reaction conditions with a Cu catalyst. Catalyzed by Cu 0.4 Mg 5.6 Al 2 , furfural can be hydrogenated and dehydrated smoothly to furfuryl alcohol, cyclopentanone, and cyclopentanol in high yields, respectively. At 110 °C and under 2.0 MPa H 2 pressure, furfuryl alcohol can be obtained in 99.5% yield. Moreover, the Cu 0.4 Mg 5.6 Al 2 catalyzed hydrogenation of furfural in water gave cyclopentanol in 98.6% yield. Additionally, cyclopentanone can also be obtained in 98.1% yield. The catalyst Cu 0.4 Mg 5.6 Al 2 can be reused several times with only slightly deactivation. Additionally, the hydrogenation of furfural gave well to excellent yield of cyclopentanol in high concentration (15−30 wt % solution of furfural in water), which improved the practicability and efficiency of the process. The hydrogenation of furfural is high efficient, practical and green process of biomass application.
The lack of strength and damage tolerance can limit the applications of conventional soft magnetic materials (SMMs), particularly in mechanically loaded functional devices. Therefore, strengthening and toughening of SMMs is critically important. However, conventional strengthening concepts usually significantly deteriorate soft magnetic properties, due to Bloch wall interactions with the defects used for hardening. Here a novel concept to overcome this dilemma is proposed, by developing bulk SMMs with excellent mechanical and attractive soft magnetic properties through coherent and ordered nanoprecipitates (<15 nm) dispersed homogeneously within a face‐centered cubic matrix of a non‐equiatomic CoFeNiTaAl high‐entropy alloy (HEA). Compared to the alloy in precipitate‐free state, the alloy variant with a large volume fraction (>42%) of nanoprecipitates achieves significantly enhanced strength (≈1526 MPa) at good ductility (≈15%), while the coercivity is only marginally increased (<10.7 Oe). The ordered nanoprecipitates and the resulting dynamic microband refinement in the matrix significantly strengthen the HEAs, while full coherency between the nanoprecipitates and the matrix leads at the same time to the desired insignificant pinning of the magnetic domain walls. The findings provide guidance for developing new high‐performance materials with an excellent combination of mechanical and soft magnetic properties as needed for the electrification of transport and industry.
The local variation of grain boundary atomic structure and chemistry caused by segregation of impurities influences the macroscopic properties of polycrystalline materials. Here, the effect of co-segregation of carbon and boron on the depletion of aluminum at a Σ5 (3 1 0 )[0 0 1] tilt grain boundary in a α − Fe-4 at%Al bicrystal is studied by combining atomic resolution scanning transmission electron microscopy, atom probe tomography and density functional theory calculations. The atomic grain boundary structural units mostly resemble kite-type motifs and the structure appears disrupted by atomic scale defects. Atom probe tomography reveals that carbon and boron impurities are co-segregating to the grain boundary reaching levels of >1.5 at%, whereas aluminum is locally depleted by approx. 2 at.%. First-principles calculations indicate that carbon and boron exhibit the strongest segregation tendency and their repulsive interaction with aluminum promotes its depletion from the grain boundary. It is also predicted that substitutional segregation of boron atoms may contribute to local distortions of the kite-type structural units. These results suggest that the co-segregation and interaction of interstitial impurities with substitutional solutes strongly influences grain boundary composition and with this the properties of the interface.
Multiprincipal‐element alloys (MPEAs), including high‐entropy alloys, are a new class of materials whose thermodynamical properties are mainly driven by configuration entropy, rather than enthalpy in the traditional alloys, especially at high temperatures. Herein, the design of a novel soft‐magnetic nonequiatomic, quaternary MPEA is described, via tuning its chemical composition to deliberately manipulate its microstructure, such that it contains ultrafine ferromagnetic body‐centered‐cubic (BCC) coherent nanoprecipitates (3–7 nm) uniformly distributed in a B2‐phase matrix. The new alloy Al1.5Co4Fe2Cr exhibits high saturation magnetization (MS = 135.3 emu g‐1), low coercivity (HC = 127.3 A m‐1), high Curie temperature (TC = 1061 K), and high electrical resistivity (ρ = 244 μΩ cm), promising for soft magnets. More importantly, these prominent soft‐magnetic properties are observed to be retained even after the alloy is thermally exposed at 873 K for 555 h, apparently attributable to the excellent stability of the coherent microstructure. The versatility of the magnetic properties of this new alloy is discussed in light of the microstructural change induced by tuning the chemical composition, and the enhanced performance of the alloy is compared directly with that of the traditional soft‐magnetic alloys. The perspective is also addressed to design high‐performance soft‐magnetic alloys for high‐temperature applications.
A cross-correlative precession electron diffraction – atom probe tomography investigation of Cr segregation in a Fe(Cr) nanocrystalline alloy was undertaken. Solute segregation was found to be dependent on grain boundary type. The results of which were compared to a hybrid Molecular Dynamics and Monte Carlo simulation that predicted the segregation for special character, low angle, and high angle grain boundaries, as well as the angle of inclination of the grain boundary. It was found that the highest segregation concentration was for the high angle grain boundaries and is explained in terms of clustering driven by the onset of phase separation. For special character boundaries, the highest Gibbsain interfacial excess was predicted at the incoherent ∑3 followed by ∑9 and ∑11 boundaries with negligible segregation to the twin and ∑5 boundaries. In addition, the low angle grain boundaries predicted negligible segregation. All of these trends matched well with the experiment. This solute-boundary segregation dependency for the special character grain boundaries is explained in terms of excess volume and the energetic distribution of the solute in the boundary.
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