Cobalt-aluminum intermetallics

The lattice of vanadium expands approximately linearly with the addition of aluminum [64]. The aluminum intermetallic compound, V3AI (V-25 atom% Al), expands the lattice by about 1% from 0.3025 nm in unalloyed vanadium to 0.3054 nm [64]. Molybdenum, cobalt and titanium also expand the lattice of vanadium, whereas elements such as chromium and iron cause the lattice to contract [83]. Addition of these elements can increase the mechanical strength of alloys relative to unalloyed vanadium [85]. For niobium and tantalum, mechanical properties can also be improved by alloying [86]. Buxbaum has patented a number of alloys of niobium, tantalum and vanadium for membrane use, including Ta-W, V-Co, V-Pd, V-Au, V-Cu, V-Al, Nb-Ag, Nb-Pt, Nb-Pd, V-Ni-Co, V-Ni-Pd, V-Nb-Pt, and V-Pd-Au [45]. 

Skeletal copper is best made from the CuA12 intermetallic compound which has very close to 50 wt% aluminum in the alloy and gives an active and selective catalyst [27-29], Skeletal nickel is also best made from an alloy of about 50 wt% aluminum [25] however, in this case, the alloy consists of more than one intermetallic phase, the combination of which provides the best activity while maintaining adequate strength in the catalytic residue. The most active skeletal cobalt catalysts are made from an alloy of about 60-65 wt% aluminum, which consists of two intermetallic phases, Co2A19 + Co4A113 [30],... 

In the anode reaction, charge takes place from left to right and discharge occurs in the opposite direction. The metal is an intermetallic AB5-type compound. Some variation occurs in that a rare-earth mixture (typically cerium or lanthanum) is compounded with nickel, manganese, cobalt, or aluminum (for the B portion). Titanium and vanadium can also be used in AB2 intermetallic compounds with nickel, zirconium cobalt, or chromium (as the B portion), but they are rarely used due to performance issues. 

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