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    CoCrFeNiX (X=Mn, Cu) high entropy alloys (HEAs) were prepared by powder metallurgy. The effects of milling time and milling speed on the microstructures and properties of CoCrFeNiX (X=Mn, Cu) HEAs were studied. The results show that at high rotational speed, the particle size of the HEA powders is refined and is tended to be uniform, and obvious solid solution phenomenon occurs; the microstructure of CoCrFeNiMn HEA is mainly composed of BCC solid solution, FCC solid solution and CoNiCr intermetallic compound; with the increase of ball milling time, Cr-rich phase and CoNiCr compound decrease. The microstructure of CoCrFeNiCu HEA is mainly composed of BCC solid solution and FCC solid solution; with the increase of ball milling time, Ni-rich FCC solid solution is gradually replaced by Co-rich and Ni-rich FCC solid solution. CoCrFeNiMn and CoCrFeNiCu HEAs have higher compressive strength, compression ratio and hardness, and they are 1300 Mpa and 1100 Mpa, 34% and 33%, 400 HV and 350 HV, respectively; The friction coefficient curve of CoCrFeNiMn HEA is more stable than that of CoCrFeNiCu HEA.
    High-Entropy Alloys
    Solid solution strengthening
    Powder Metallurgy
    A study was carried out to compare the rates of absorption of nickel from two nickel complexes and two nickel salts in the West African Dwarf (WAD) goat. Treatments consisted of oral administration of 5mg equivalents of elemental nickel from nickel sulphate hexahydrate (NiSO4.6H2O); nickel chloride hexahydrate (NiCl2.6H2O); nickel sodium monofluorophosphate (Ni-SMFP) complex and nickel-chloroquine (Ni-Clrq) complex. Changes in the plasma levels of nickel were monitored until the concentration declined. Nickel absorption into the blood was in the order: Ni-SMFP>NiClrq>NiSO4.6H2O>NiCl2.6H2O indicating that nickel is more readily available to goats in the complex forms. JARD Vol. 1 2001: pp. 23-30
    Citations (1)
    This study is about the effect of the martensite volume fraction and indentation load on microhardness profiles of dissimilar types Dual Phase steels and DC04 mild steel. Experimental investigations were performed by mickrovickers method with using of eight different indentation loads from 0.01 kp up to 1 kp. Besides, microscope and tensile tests were carried out to complete the estimation.The hardness profiles show similar characteristics in case of all examined steels independent from the microstructure. In the lowest load ranges at 0.01 and 0.025 kp (HV0.01 and HV0.025), there are no appropriate approximations with the martensite volume fraction, due to the high deviation of the hardness results which caused by the little indentation geometry. In higher ranges, above 0.05 kp (HV0.05), linear evaluations could be applicable. With the utilization of the fitted parameters, a definite relationship is reported in the hardness values and even in the strength and elongation properties with the martensite content. Based on these correlations such contexts are added which make contact between microhardness and strength values for the practice. The discrepancy between the measured and calculated results stay under 10 HV which is less than 5%.
    Volume fraction
    Indentation
    Dual-phase steel
    Elongation
    Citations (14)
    A characterization study was undertaken with eighteen kinds of nickel/alumina impregnated catalysts prepared by using three nickel compounds (nickel (II) acetylacetonate, nickel (II) acetate and nickel (II) chloride) as the nickel source material and by applying two impregnation methods (single and multiple). The catalysts prepared by using nickel (II) acetylacetonate and nickel (II) acetate showed a similar distribution and average of nickel particle diameters regardless of nickel source material or impregnation method. The distribution broadening and the average increased with increasing nickel content for the catalysts prepared by using nickel (II) chloride. The rate of benzene hydrogenation was proportional to the nickel surface area regardless of nickel source material or impregnation method.
    Citations (5)
    Abstract Reduction of anhydrous nickel(II) compounds in the presence of diazadienes RN=CR'-CR' = NR, |(DAD), yields (DAD) 2 Ni(0). This complex 1 with R = CH(i-C 3 H 7 ) 2 is especially reactive and comproportionates with DADNiBr 2 (2) to yield the bromobridged dimeric nickel(I) species (DADNiBr) 2 (3). The crystal and molecular structure of 3 has been determined by single crystal X-ray diffraction: Space group Pbca with a = 1225.8(12), b = 1474.8(14) and c = 2167.4(22) pm; Ra = 0.076, 1034 reflections. Catalytic tetramerisation of substituted alkynes with 1 is discussed in view of the very easy formation of dimers 3.
    Anhydrous
    Citations (49)
    Properties, manipulations, preparative methods and typical reactions have been described for the following twelve representative nickel compounds which have been used and/or should be useful as catalysts and/or reagents for synthetic organic reactions : nickel (II) halides, his (acetylacetonato) -nickel (II), nickel peroxide, dichloro (bipyridyl) nickel (II), dihalobis (trialkylphosphine) nickel (II), dichlorobis (triphenylphosphine) nickel (II), dichloro {1, 3-his (diphenylphosphino) propane} nickel (II), trans-chlorophenylbis (triphenylphosphine) nickel (II), tetracarbonylnickel (0), bis (η- 1, 5-cyclooctadienyl) nickel (0), tetrakis (triphenylphosphine) nickel (0), di-μ-bromobis (1-3-η-allyl) dinickel (II).
    Peroxide
    Li-Mg-Al-Ti-M based lightweight high entropy alloys (lightweight HEAs) were synthesized through mechanical alloying and the possibility of solid solution formation was systematically investigated. The quaternary Li-Mg-Al-Ti system exhibited a HCP structure. Solid solutions were formed in the alloys with V or Nb among the 15 types of LiMgAlTiM alloys. Furthermore, distinct BCC single phase solid solution were successfully synthesized by adjusting the composition of the Li-Mg-Al-Ti-V system. The typical indicators of solid solution formation which have been used in HEAs were applied to this study. As a result, it was found that the effective indicators for mechanical alloying differ from those used in conventional melting methods, meaning their dependency on the alloy fabrication process.
    High-Entropy Alloys
    Solid solution strengthening
    Nickel allergy is the most frequent contact allergy and is also one of the major background factors for hand eczema. The clinical significance of nickel release from coins was discussed when the composition of euro coins was decided. Current European coinage is dominated by cupro-nickel coins (Cu 75; Ni 25); other nickel-containing and non-nickel alloys are also used. Nickel release from used coinage from the UK, Sweden and France was determined. It was shown that nickel ions are readily available on the surface of used coins. After 2 min in artificial sweat, approximately 2 microg of nickel per coin was extracted from cupro-nickel coins. Less nickel was extracted from non-nickel coins. Nickel on the surface was mainly present as chloride. After 1 week in artificial sweat approximately 30 microg/cm2 was released from cupro-nickel coins: less nickel was released from coins made of other nickel alloys. Theoretically, several microg of nickel salts may be transferred daily onto hands by intense handling of high-nickel-releasing coins.
    Nickel allergy
    numismatics