Theoretical analysis of the conditions required for rendering metallic alloys amorphous during gas-thermal spraying. II. Phase formation during solification of the sprayed material

Translated from Poroshkovaya Metallurgiya, No. 10, pp. 11–15, October, 1992.     

Structurization of Coatings in the Plasma Arc Spraying Process Using B4C + (Cr,Fe)7C3-Cored Wires

Powder Metallurgy and Metal Ceramics - The structure and phase composition acquired by coatings deposited in optimum mode by the plasma arc spraying process were examined. The spraying materials...     

Structural transformations occurring in flame-sprayed Ni60Nb40 alloy coatings during heating in the presence of oxygen

Conclusions During the heating of flame-sprayed Ni₆₀Nb₄₀ alloy coatings in the presence of oxygen the process of crystallization of their amorphous matrix occurs at T > 750°K through the formation of the niobium oxide Nb₂U₅ and precipitation of nickel. Decomposition of the amorphous matrix is accompanied by a decrease in length of the coatings. The oxidation of niobium at 750–890°K prevents the formation of the equilibrium phases of the Ni-Nb system during the crystallization of the amorphous structure. During heating in the 890–1110°K range the metastable Ni₈Nb phase is present in the coatings.Translated from Poroshkovaya Metallurgiya, No. 12(300), pp. 21–26, December, 1987.     

Studying the statistical indicators of the radiation hardness of PWO crystals for the barrel of the electromagnetic calorimeter of the CMS project

The results from experimental and certification measurements of the optical transmission and technical light yield of a technological lot of PWO crystals intended for the central part of the CMS electromagnetic calorimeter at CERN are analyzed. Statistical estimates of the crystals radiation hardness are obtained, allowing the calorimeter energy resolution to be evaluated under operating irradiation conditions.__________Translated from Pribory i Tekhnika Eksperimenta, No. 2, 2005, pp. 71–77.Original Russian Text Copyright © 2005 by Dormenev, Annenkov, Borisevich, Drobyshev, Korzhik, Rudov.     

Structural characteristics of flame-sprayed Fe-Ni-B alloy coatings

Conclusions Flame-sprayed Fe₄₀Ni₄₀B₂₀ alloy coatings have a mainly amorphous structure with a small amount of fine, 0.5- to 1-m.crystalline inclusions. The crystalline phases are (Fe, Ni)₃B and Fe_x Ni₂₃-_xB₆. The structure of the precipitated crystalline inclusions in the amorphous matrix is not related to that of the eutectic of the starting alloy powder used for spraying. In the direction from the base to the free surface the coating structure varies: The volume concentration of the crystalline phases changes, which is reflected in the emission of secondary ions of the main components of the deposited alloy.Translated from Poroshkovaya Metallurgiya, No. 11(299), pp. 22–25, November, 1987.     

Lead tungstate scintillation crystals with improved light yield for experimental high-energy physics

The possibilities of improving the light yield of lead tungstate (PbWO₄) crystals (PWO) for application in experimental high-energy physics in the particle energy range from 10 MeV to tens of teraelectronvolts are considered. The results of investigations of the scintillation properties of PWO crystals, which were doped with La and Y ions, performed at low (?25°C) and room temperatures are presented.     

A Method for Calculating the Scintillation Light Collection Time in PWO Crystals

A method for estimating the scintillation light collection time in PWO crystals is proposed. This method has a low sensitivity to statistical noise due to the integration of experimental data over a wide time range. As a result, the data acquisition time can be reduced. The method is noniterative, so that the calculation time is significantly reduced, and the operation is simplified. This method is used for the certification of PWO scintillation crystals in their mass production.     

Theoretical analysis of the conditions required for rendering metallic alloys amorphous during gas-thermal spraying

Translated from Poroshkovaya Metallurgiya, No. 9(357), pp. 56–61, Septemebr, 1992.     

Structural transformations in thermal spray coatings of Ni60Nb40 alloy in vacuum annealings

Conclusions Thermal spray coatings of Ni₆₀Nb₄₀ alloy have primarily an amorphous structure with inclusions of Nb0₂, Ni₃Nb, Ni, and NiO crystalline phases. In the original powder the oxide phases and pure nickel are absent. Under conditions of vacuum anneals the amorphous structure is preserved up to 800°K. Heating of the coatings within the limits of their temperature stability does not change the morphology of the surfaces of the fractures, which is characteristic of amorphous alloys. Heating to the crystallization temperature of the amorphous matrix and above leads to loss of the elasticity and plasticity characteristic of the coatings in the original condition.Oxidation of the niobium during spraying and subsequent precipitation of its oxides in heating changes the sequence of crystallization from the amorphous matrix of stable phases and causes initial precipitation of a phase rich in nickel. Crystallization of the amorphous structure occurs in two basic stages, precipitation of Ni₃Nb and of -NiNb.Translated from Poroshkovaya Metallurgiya, No. 10(286), pp. 39–45, October, 1986.