Mo Clusters Research Articles

Substitutional-interstitial interactions in Ta-Re-N and Ta-Re-O alloys

Anelastic techniques have been employed to determine the extent of substitutional-interstitial interactions in Ta-Re-N and Ta-Re-O alloys. Analyses of the concentration and temperature dependence of Snoek-type anelasticity in these alloys has disclosed that unassociated N atoms and N atoms in ReN and Re 2N clusters relax in Ta-Re-N alloys. The binding enthalpies of the Re-N clusters are ΔH b ( ReN) = 3200 ± 600 cal/mole and ΔH b ( Re 2 N) = 4700 ± 2000 cal/mole. There appear to be only small changes in the specific (unit) relaxation strength of N in Ta when it clusters with one or two Re atoms. A wide spectrum of Re mO clusters, where m = 0–3, exhibit relaxation in Ta-Re-O alloys. The binding enthalpies of Re-O clusters are probably larger than for Re-N clusters, but the complex nature of the anelastic spectra precludes a quantitative determination.

Superconductivity and structural behavior of hexagonal MoN and related Mo compounds

The results of high-pressure synthesis of hexagonal MoN are reported. Its transition temperature T c is in the range 14.8°–13°K. The high T c superconductivity is related to the presence of a superlattice, caused by clustering of Mo. The occurrence of Mo clustering in other superconducting or nonsuperconducting Mo compounds is discussed.

Catalytic properties of some Mo 3-cluster compounds prepared in high surface area

Catalytic properties of some Mo 3-cluster compounds prepared in high surface area

On the Mechanical Behavior of Fe-Mo Alloys

The yield stress of high purity Fe (less than 10 wt. ppm (C+N) content) containing 0, 1.14, 2, 4 and 6 at % Mo in solution was investigated at temperatures from 77 to 300°K. At 300°K, the yield stress varies linearly with Mo content. At low temperatures, alloy softening occurs with a minimum in the yield stress at about 2 at. % Mo; for higher concentrations, the variation of yield stress with Mo concentration is linear with the same slope as that obtained at 300°K. Our results suggest that the Mo atoms in solution have mainly an athermal influence on the yield stress and that the alloy softening is due to a scavenging process. The influence of Mo clusters in the Fe-6% Mo alloy was studied and it was found that they do not contribute to the yield stress.