Angular distribution of sputtered atoms from polycrystalline metal targets with crystallographic-preferred orientation was measured for 0.5- and 1.0-keV Ar+ ions at incidence angles of 0° and 45°. The distribution was compared with that for a Si (100) single-crystal target. Atoms sputtered from Au, Pt, Al, and NiFe targets are ejected preferentially in the directions of their close packing in the lattice. For the Si target, the distribution is under cosine. These results are explained in terms of the target-surface crystal structure during and after ion bombardment. The surface structure for the metal targets remains essentially unchanged, but not for the Si target. Sputtered-atom ejection along the target normally increases with increasing incident-ion energy. Even at oblique incidence, heavy-target atoms such as Au, appear to have preferentially ejected atoms in the close-packed directions.

No abstract

Effect of nickel and nitrogen contents on stress corrosion cracking (SCC) of 22%Cr-3%Mo-base duplex stainless steel was investigated in simulated sour environments with respect to both the base metal and the heat-affected zone (HAZ) of welding. The threshold stress and the critica) chloride concentration for SCC ware evaluated as a function of the ferrite content (a-content) in the alloy. The threshold stress is highest at the a-content of 40 to 45%, and is lowered with decreasing and increasing the a-content from its value. The alloy whose a-content exceeds 80% at the HAZ has also high susceptibilities to pitting corrosion and intergranular corrosion (IGC). The critica) chloride concentration for cracking increases with the decrease in the a-content. Moreover, the contents of chromium, nickel and molybdenum in the a-phase are considered to be an important factor for determining the critica) chloride concentration.KEY WORDS: duplex stainless steel, sour environment, stress corrosion cracking. ABSTRACTThe effect of Cr, Ni, and Mo contents of Ni-base alloy on the corrosion behavior in H2S-0O2-C1 environment with elemental sulfur at elevated temperature was investigated. The environmental with elemental sulfur was more corrosive than that without elemental sulfur. The stress corrosion cracking (SSC) resistance of Ni-base alloys increases with increasing Ni and especially Mo contents. The main effect of the elemental sulfur is considered that the generation of H2S due to the cathodic reaction of elemental sulfur at a location underneath sulfur deposftion, which is related to the viscosity of elemental sulfur. Recommendable chemical composition of Ni-base alloys in H2S-CO2-C1--S environment was proposed trom the view points of phase stability, stress corrosion cracking, and hydrogen embrittlement (HE). Suitable high-Ni alloys had more than 12%Mo and 15%Cr and the phase stability parameter (Md) value below 0.911.

No abstract

No abstract