Bombardment-induced segregation and redistribution

Conference · Tue Apr 01 00:00:00 EST 1986

OSTI ID:5462606

Lam, N Q; Wiedersich, H

During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a compositionally-modified layer in the subsurface region. In the present paper, selected examples of these different phenomena and their synergistic effects on the evolution of the near-surface compositions of alloys during sputtering and ion implantation at elevated temperatures are discussed. 74 refs., 7 figs., 1 tab.

• Research Organization: Argonne National Lab., IL (USA). Materials Science and Technology Div.
• DOE Contract Number: W-31-109-ENG-38
• OSTI ID: 5462606
• Report Number(s): CONF-8606191-1; ON: DE86014535
• Resource Relation: Conference: International symposium on sputtering, Vienna, Austria, 2 Jun 1986
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ION BEAM TARGETS
SURFACE PROPERTIES
COPPER ADDITIONS
GOLD ADDITIONS
ION IMPLANTATION
NICKEL ALLOYS
REACTION KINETICS
SPUTTERING
TEMPERATURE DEPENDENCE
THEORETICAL DATA
ALLOYS
COPPER ALLOYS
DATA
GOLD ALLOYS
INFORMATION
KINETICS
NUMERICAL DATA
TARGETS
360104* - Metals & Alloys- Physical Properties
640301 - Atomic
Molecular & Chemical Physics- Beams & their Reactions