372595888

FERROUS METALS

JPRS-UMS-92-003 16 March 1992

The Effect of Argon łon Channeling on the Sputtering of a Niobium Monocrystal Surface

927D0067A Moscow POVERKHNOST: FIZIKA, KHIMIYA, MEKHANIKA in Russian No 12, Dec 91 (manuscript received 27 Jun 90; after remion 4 Jun 90) pp 105-111

[Article by A.A. Kosyachkov, V.T. Cherepin, and S.M. Chichkan, Metal Physics Institute, UkSSR Academy of Sciences, Kiev]

UDC 537.534.8

[Abstract] The authors of the study used the method of secondary-ion emission [SIE] anisotropy to isolate the individual types of ion channels occurring during the sputtering of a niobium monocrystal surface and to subsequently determine the effect of argon ion channeling on the sputtering. During their studies they used a new angular resolution instrument that permitted freer selection of the direction of surface irradiation and analysis of the sputtered ions. The surfaces of well-oriented Nb (100) and Nb (111) monocrystals were bombarded with Arf ions with energies of 3, 5, and 7 keV at an ion current density of 5 x 10‘^cm'² xs'' in a beam with a spread not exceeding 1°. The polar and azimuthal bombardment angles were established with a precision of 0.5°. An electrostatic lens was used to level the spatial and energy anisotropy of the probability of the sputtered ions’ ionization. The sputtering of clusters was taken into account by summing the yields of the Nb⁺n (n = 1 to 6) cluster ions. In accordance with the established prac-tice, the effect of channeling on the anisotropy of SIE was determined as the relative difference between the max-imum and minimum ion yields measured at one and the same polar glide angle. The contributions madę by the individual channeling components to the reduction in output of secondary ions was assumed to be additive. The studies performed confirmed that channeling of bombarding Ar'*' ions parallel to the most open (110) planes of the body-centered crystal lattice make the greatest contribution to the reduction in output of sputtered particles. When compared with this, the contribution of planar (100) channeling is insignificant. The studies also established that the amount of contrast may be altered by morę than a factor of 2 depending on the slope of the channeling piane relative to the target surface. By analogy in the case of axial channeling, the incline of the axial channel relative to the crystal surface may have a morę significant effect on SIE anisotropy than channel transparency does. The contribution from the most transparent channels, i.e., (111) and (100), is commensurate with that of planar channeling. The pos-sible channeling along the (112), (113), and (115) axes, on the other hand, has no influence on the orientation effects of sputtering. Increasing the energy of the bombarding argon ions from 3 to 7 keV was found to improve contrast and reduce the angular half-widths of the minima of the azimuthal distributions of the SIE. The studies performed thus confirmed the feasibility of the authors’ proposed technique to quantitatively esti-mate the individual contributions of axial and planar channeling of Ar* ions. Figures 3, tables 2; references 7: 5 Russian, 2 Western.

Development and Implementation of Low-Sulfur Steel-Making Pig Iron Smelting Under Southern USSR Conditions

927D0061B Moscow STAL in Russian No 12, Dec 91 pp 7-12

[Article by S.N. Pryadko, V.I. Malkin, S.L. Yaro-shevskiy, V.V. Starov, I.D. Tsybulenko, Z.K. Afa-nasyeva, ICramatorsk Metallurgical Works, Donetsk Polytechnic Institute, and Bakal Ore Directorate]

UDC 669.162.2

[Abstract] The increasingly stringent requirements being imposed on the sulfur content in various brands of steel-making pig iron and the specific operating conditions of blast fumaces in the south of the USSR which in many respects are inferior to those in the east are discussed. The development and implementation of pro-cesses and materials for smelting low-sulfur steel-making pig iron in Southern blast fumaccs are addressed; to this end, the Chemical composition of iron ore materials and coke characteristics for smelting Steel with a Iow sulfur content are summarized and kinetic ore reduction curves are plotted. The dependence of slag viscosity and melting point on the magnesia concentration is cxamined. Com-parative performance indicators of blast fumace No. 4 at the ICramatorsk Metallurgical Works with siderite added to the burden are cited and the Chemical composition of magnesian slags at the Kramatorsk Metallurgical Works is analyzed. Curves of the dependence of slag basicity on the desulfurization coefficient and the dependence of the sulfur content in pig iron on the slag basicity and Silicon content are plotted. An analysis shows that the usc of low-melting stable magnesian slags is the most important and indispensable element for producing conversion pig iron with a sulfur content of 0.02% or below and that an increase in the MgO content to 6-12% in slag with a 1.35-1.45 basicity lowers the melting point by 20 to 100°C, reduces viscosity by 0.18-0.65 Pa x s, and increases the stability of the slag’s physical properties by two- to sevenfold. The impact of siderite addition to the charge is assessed. Figures 5; tables 3; references 15.

Metal Jet Drop Height During In-Line Vacuum Degassing of Continuously Cast Steel: Discussion

927D0061F Moscow STAL in Russian No 12, Dec 91 pp 24-25

[Article by A.A. Smimov, Uralmash Production Associa-tion]

UDC 621.74.047-982-715.6

[Abstract] Analyses of the degree of metal refining in a vacuum as a function of the jet drop height performed by