Estimation of site occupancy error due to statistical noise for the ratio ALCHEMI method[Atom Location by Channeling Enhanced Microanalysis]
The ALCHEMI (acronym for atom location by channeling enhanced microanalysis) method has been widely used to determine crystallographic site distributions of substitutional species within a host crystal. However, the error of site occupancy can not be easily determined for the ratio ALCHEMI method. The purpose of this paper is to present a detailed treatment of error due to statistical noise for the ratio ALCHEMI method, with specific reference to the site occupancy of alloying elements in TiAl. The formulae for calculating the site occupancy of alloying elements in an ordered phase derived by Spence and Taftoe and by Taftoe and Spence are first expressed in different forms. Then the path of error propagation in the calculation is described and the maximum error of site occupancies caused by statistical noise is estimated. Finally, the authors present experimental measurements of site occupancy made with representative elements that were known to occupy exclusively either the Ti or the Al sublattice sites in TiAl in order to test the reliability of the error-analysis method they described. The error due to delocalization interaction for the planar ALCHEMI method will also be discussed for the case of TiAl.
- Research Organization:
- Chinese Academy of Sciences, Inst. of Metal Research, Shenyang (CN)
- OSTI ID:
- 20006434
- Journal Information:
- Scripta Materialia, Vol. 41, Issue 12; Other Information: PBD: 19 Nov 1999; ISSN 1359-6462
- Country of Publication:
- United States
- Language:
- English
Similar Records
Reliability of sublattice occupancies determined by ALCHEMI
Determination of site-occupancies in aluminide intermetallics by ALCHEMI