Formation Of Supersaturated Solid Solution Research Articles

Hard chrome and molybdenum coatings produced by physical vapour deposition

Coatings of solid solutions of carbon or nitrogen in chromium or molybdenum were prepared by cathodic magnetron sputtering. Carbon or nitrogen was introduced either through the gas phase by reactive sputtering or by direct sputtering of sintered composite targets. Chemical and structural analyses of films revealed the formation of supersaturated solid solutions for carbon or nitrogen concentrations of up to several weight per cent. The nitrade and carbide phases predicted from the binary diagrams were not observed. The Cr-C and Mo-C coatings showed hardnesses of up to 2500 HV. The hardnesses of Mo-N and Cr-N reached 3000 HV. The wear and corrosion resistance of these coatings, which showed a dense structure, was superior to that of electrolytic hard chrome.

Plastic Deformation of Vanadium Single Crystals during High-Dose Arsenic-Ion Implantation

Implantation of As ions into (111) surfaces of V single crystals at room temperature results in the formation of supersaturated solid solution. Channeling studies revealed that at 14 at.% As the implanted region starts to rotate with respect to the bulk. The angle of rotation is perpendicular to a (110) plane, the slip plane, and increases with increasing As concentration. At 20 at.% As polygonization of the implanted region occurs. Results from (110) surfaces support the assumption that the implantation process causes a slip mechanism which gives rise to the rotation and the polygonization of the implanted layer.

Metastable phases in vapour-deposited Al-Ru alloys

Vapour deposition of two Al-Ru alloys containing 10 and 15wt% Ru resulted in the formation of supersaturated solid solutions. Electron microscopy and electron diffraction techniques have been used to characterize this as-quenched structure and also those formed on subsequent decomposition. Elevated-temperature (650–800 K) annealing treatments resulted in the formation of a metastable intermediate phase. Electron diffraction evidence suggested that this phase can be assigned a simple cubic structure either of the Mo3N2-type witha=0.42 nm or of the Mg2Zn11-type witha=0.84 nm. Further annealing led to the formation of the equilibrium AI and AI6 Ru phases. The morphology and structural features of transformation products and the crystal structure details of the metastable intermediate phase have been discussed.

Peritectic transformations in crystallization of alloys of the Al-Cr system. I

Established laws of the nonequilibrium crystallization of aluminum-chromium alloys permit the conclusion that each peritectic horizontal on the diagram of the Al-Cr system (at 725, 930, and 1000°C) corresponds to a region of structural transformation to a liquid extending from aluminum is the vertical of an intermediate compound. Retention of the stability of the high-temperature structural state of the liquid during its cooling predetermines the possibility of a delay in the peritectic transformation, crystallization according to metastable diagrams and, in individual cases, the formation of supersaturated solid solutions based on aluminum.

電析Ａｕ‐Ｎｉ合金の微細構造と相に関する電子顕微鏡的研究

The microstructure and phase of Au-Ni alloys electrodeposited from citric acid-cyanide acidified baths were studied by utilizing T. E. M. and S. E. M. and also by measuring microhardness. The electrodeposited alloys were found to form supersaturated solid solutions on the side of Au with a limit up to about 45at. % Ni, and also on Ni side with about 95at. % or more Ni. Over the at. % range of Ni from about 45 to 95, metastable intermediate phases, which probably have similar structures to the phases of AuNi and/or AuNi3 in metallurgically melted Au-Ni alloys, coexisted with the supersaturated solid solutions. Film growth by electrodeposition was of the following process: nucleation→island crystal→network crystal→plate crystal. Also, microcrystallites of 50-200Å in size and many microtwins were observed in the plate crystals of the films. In the initial stage of electrodeposition the film growth took place coherently with Cu substrates. The thick films deposited for 60min, on the other hand, showed smooth surfaces and the smoothness increased with increasing Ni content of the alloys. Formation of supersaturated solid solutions and metastable intermediate phases caused an increase in the film hardness. A maximum value of Hv=400 was obtained at about 80at. % Ni, but the alloys containing about 63-90 at. % Ni were brittle.