TY - JOUR
T1 - Statistical ALCHEMI
T2 - General formulation and method with application to Ti-Al ternary alloys
AU - Rossouw, C. J.
AU - Forwood, C. T.
AU - Gibson, M. A.
AU - Miller, P. R.
PY - 1996/1/1
Y1 - 1996/1/1
N2 - Recent advances in the theory of characteristic X-ray emission from crystals under dynamic electron diffraction conditions are used in developing a new fully quantitative statistical method for atom location by channelling-enhanced microanalysis (ALCHEMI). Limitations imposed by delocalization, disorder and occupancy of interstitial sites are clarified. A fully computerized method for automated data collection and analysis from incoherent channelling patterns formed by the variation in characteristic X-ray emission as a function of orientation is used for the first time. The precision and accuracy of this method are investigated using both experimental and simulated data from the ordered y- phase in ternary Ti-Al alloys. It is shown that 1 at.% Ga, Hf and Mo additions partition onto A1 sites, Ti sites and both sites respectively, and contrast in X-ray incoherent channelling patterns confirms that these ternary atoms are not located on interstitial sites. The traditional ratio ALCHEMI technique is shown to have severe limitations in comparison with statistical methods.
AB - Recent advances in the theory of characteristic X-ray emission from crystals under dynamic electron diffraction conditions are used in developing a new fully quantitative statistical method for atom location by channelling-enhanced microanalysis (ALCHEMI). Limitations imposed by delocalization, disorder and occupancy of interstitial sites are clarified. A fully computerized method for automated data collection and analysis from incoherent channelling patterns formed by the variation in characteristic X-ray emission as a function of orientation is used for the first time. The precision and accuracy of this method are investigated using both experimental and simulated data from the ordered y- phase in ternary Ti-Al alloys. It is shown that 1 at.% Ga, Hf and Mo additions partition onto A1 sites, Ti sites and both sites respectively, and contrast in X-ray incoherent channelling patterns confirms that these ternary atoms are not located on interstitial sites. The traditional ratio ALCHEMI technique is shown to have severe limitations in comparison with statistical methods.
UR - http://www.scopus.com/inward/record.url?scp=0041113835&partnerID=8YFLogxK
U2 - 10.1080/01418619608239690
DO - 10.1080/01418619608239690
M3 - Article
AN - SCOPUS:0041113835
SN - 0141-8610
VL - 74
SP - 57
EP - 76
JO - Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
JF - Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
IS - 1
ER -