Alloys Ni with

The overall effects of alloying Ni with Cu can now be summarized as follows Skeletal reactions are strongly suppressed, hydrogenolysis more than isomerization, but a part (one type) of isomerization running via the 3C complexes is affected less by alloying there is no indication of isomerization on Ni via the 5C complexes. 

The experimental data indicate that the interaction between CO and glassy metals is controlled by electronic effects. Alloying Ni with Zr changes the local electronic structure at the Ni site and increases the electron density in the antibonding 27r molecular orbital of the adsorbed CO. This occurs through back-donation from the Ni 3d band and weakens the C—O bond. Thus, the potential barrier for CO dissociation is lowered. On Cu50ZrSo, CO dissociates at all exposures and only Zr is oxidized (35). 

Thorium metal alloys readily with a large number of metals, including Fe, Co, Ni, Cu, Au, Ag, B, Pt, Mo, W, Ta, Zn, Bi, Pb, Hg, Na, Be, Mg, Si, Se, and Al. Like many electropositive metals, finely divided thorium metal is pyrophoric in air, and bums to give the oxide. Massive metal, chips, and turnings... 

Fig. 22. Charge A and discharge B curves of (- ) a Ni—H(MH) cell employing AlniNi A[q 3C0Q alloy compared with those of (-)...

For resistance against fatigue, Nimonic 75 has been used with Nimonic 80 and Nimonic 90. Nimonic 75 is an 80-20 nickel-chromium alloy stiffened with a small amount of titanium carbide. Nimonic 75 has excellent oxidation and corrosion resistance at elevated temperatures, a reasonable creep strength, and good fatigue resistance. In addition, it is easy to press, draw, and mold. As firing temperatures have increased in the newer gas turbine models, HA-188, a Cr, Ni-based alloy, has recently been employed in the latter section of some combustion liners for improved creep rupture strength. 

The mechanical properties of low- or medium-carbon structural steels can be improved considerably by small alloy additions. For example, 1% of chromium will raise the yield point of 0.2% carbon steel from about 280MN/m to 390MN/m. This has led to the development of a range of so-called low-alloy steels with high tensile properties. A typical example is grade 817M40 (En 24), which contains 0.4% C, 0.2% Si, 0.6%, Mn, 1.2%, Cr, 0.3% Mo and 1.5% Ni. 

Nickel silvers These wrought alloys consist essentially of Cu, Zn and Ni, with Ni in the range 10-30%. Leaded nickel brasses are also used, usually where some machining is involved. 

In addition to nickel alloys, nickel also forms an important alloying element in stainless steels and in cast irons, in both of which it confers additional corrosion resistance and improved mechanical and engineering properties, and in Fe-Ni alloys for obtaining controlled physical and magnetic properties (see Chapter 3). With non-ferrous metals nickel also forms important types of alloys, especially with copper, i.e. cupro-nickels and nickel silvers these are dealt with in Section 4.2. 

In general, the alloys listed in Table 4.21 are confined to those in which nickel is the principal alloying element, but it should be noted that highly alloyed stainless steels containing 20-30% Cr, and 20-30% Ni with additions of molybdenum and copper have some features in common with the Ni-Cr-Fe-Mo-Cu alloys given in the table. 

An interesting illustration of the effect that quite small alloying additions may sometimes have on anodic behaviour is seen in Fig. 4.27 from a comparison of the Ni-30Cu alloy Alloy 400 with its age-hardening variant Alloy K500, which contains 2-7% A1 and 0-6% Ti. The presence of these elements in the latter alloy is responsible for a well-defined passive region, whereas the former alloy shows only a slight tendency to passivate in acidic... 

When Al, Pt, Ni, or Cu is used as the substrate of lithium plating with 1 mol L 1 LiC104- PC/l, 2 -dimethoxyethane (DME), Eff decreases in the order is Al > Pt > Ni > Cu [26]. Lithium is easily alloyed electrochemically with many metals [27] the Eff values measured in these experiments could include those of lithium alloys. 

Another way to monitor the expected changes in the metal electronic structure is to look at the adsorbed molecules, which are sensitive in their properties to the changes in the electronic structure of surface metal atoms. Such a molecule is CO and the frequency of the CO stretch vibrations ( v(CO)) is a sensitive detector of the direct- and back-donation upon adsorption of CO. It has been reported, that v(CO) decreases for the VIII group metal by alloying of Pd with Ag (22), Ni with Cu (23), but also when mixing Ni with Co (24). This has been first explained (25) as an indication for an increased backdonation due to an assumed electron shift Cu Pt,... 

Nowadays, such hydride electrodes are used widely to make alkaline storage batteries which in their design are similar to Ni-Cd batteries but exhibit a considerably higher capacity than these. These two types of storage battery are interchangeable, since the potential of the hydride electrode is similar to that of the cadmium electrode. The metal alloys used to prepare the hydride electrodes are multicomponent alloys, usually with a high content of rare-earth elements. These cadmium-free batteries are regarded as environmentally preferable. 

We have found new CO-tolerant catalysts by alloying Pt with a second, nonprecious, metal (Pt-Fe, Pt-Co, Pt-Ni, etc.) [Fujino, 1996 Watanabe et al., 1999 Igarashi et al., 2001]. In this section, we demonstrate the properties of these new alloy catalysts together with Pt-Ru alloy, based on voltammetric measurements, electrochemical quartz crystal microbalance (EQCM), electrochemical scanning tunneling microscopy (EC-STM), in situ Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). 

Figure 10.1 shows 4 at various electrodes as a function of CO poisoning time at 26 °C. For the pure Pt electrode, the value of 4 decreases and reaches nearly zero after 30 minutes. In contrast, the Pt-Fe, Pt-Ni, Pt-Co, and Pt-Mo alloys retain high HOR activity for a prolonged period of time the reduction in 4 is negligibly small. Such CO tolerance of these alloys was found to be almost independent of the composition for example, alloying Pt with only 5 at% Fe resulted in excellent tolerance. However, Pt alloys with Ti, Cr, Cu, Ge, Nb, Pd, In, Sb, W, An, Pb, or Bi showed complete CO poisoning after a short time, while the combination of Pt with Mn, Zn, Ag, or Sn exhibited only limited CO tolerance. 

Quantitation is usually achieved by comparing the X-ray yields from the sample with yields obtained from standards. The ease with which measurements can be interpreted quantitatively depends on the sample. As illustrated in Fig. 7.7, the volume that is activated by the 10-100 keV electron beam has the shape of a pear with typical dimensions of a few pm. As a consequence, X-rays formed in the interior may be absorbed on their way out, and may stimulate the emission of photoelectrons, Auger electrons and again X-rays. The latter process, secondary fluorescence, can lead to an overestimate of the concentrations. For example, if the specimen is a bulk Fe-Ni alloy, Ni Ka radiation is adsorbed by iron and causes... 

Alloying of the active metal such as Ni with Cu has also been known to suppress the carbon deposition on the catalyst surface and this improved the stability of the Ni-Cu/Si02 catalyst during ethanol reforming.34... 

Gas Atomization 50-300 Standard deviation 1.9-2.5 <10-50 at high gas pressures with close-coupled atomizer Solder materials. Precious metals, Cu, Fe, Al, Mg, Co, Ti, Zn, Al-6Cr-3Fe-2Zr alloy. Low-alloy steels. High speed steels. Stainless steels, Specialty alloys, Ni-base superalloys, Alumina, Intermetallics io3-.o5 1-70 Spherical smooth particles. Cleanliness, Rapidly-solidified structures, Acceptable production rates High cost, Low 1 volume, Low energy efficiency (EE), Gas-filled porosity in particles H... 

The precursor alloy is quenched to form small grains readily attacked by the caustic solution [31], Quenching can also enable specific intermetallic phases to be obtained, although this is less common. Yamauchi et al. [32-34] have employed a very fast quench to obtain a supersaturation of promoter species in the alloy. It is even possible to obtain an amorphous metal glass of an alloy, and Deng et al. [35] provide a review of this area, particularly with Ni, Ni-P, Ni-B, Ni-Co, and Ni-Co-B systems. The increased catalytic activity observed with these leached amorphous alloy systems can be attributed to either chemical promotion of the catalyzed reaction or an increased surface area of the leached catalyst, depending on the components present in the original alloy. Promotion with additives is considered in more detail later. 

Figure 2.33. Ni-Co-O phase diagram (isothermal section at 1600 K). log p02 (oxygen partial pressure) is plotted against the molar fraction in the metallic alloy. The metallic alloy, (Ni, Co) solid solution is stable in (1) and the mixed oxide (Ni, Co)0 solid solution in (3). In the intermediate region (2) we have coexistence of alloy and oxide. For the value of the partial oxygen pressure corresponding to y, within the two-phase field, we will have the alloy of composition xt in equilibrium with an oxide containing the two metals in the ratio x2-...

NixAlj x (homogeneous between 42 and 69 at.% Ni) with good mechanical and oxidation resistance properties. By quenching from high temperatures the formation of an ordered martensite is obtained which can be considered for its shape memory behaviour. For a discussion on substitutional additions to CsCl-type alloys (site preference for dilute additions to NiAl, FeAl, CoAl, etc.) see Kao et al. (1994). 

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