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X‐ray determination of the Debye–Waller factors and order parameters of Ni 3 Al alloys
Author(s) -
Mohan Rao P. V.,
Murthy K. S.,
Suryanarayana S. V.,
Naidu S. V. N.
Publication year - 1993
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889893003395
Subject(s) - zirconium , hafnium , materials science , titanium , stoichiometry , debye model , boron , debye , analytical chemistry (journal) , ternary operation , aluminium , metallurgy , chemistry , thermodynamics , physics , organic chemistry , chromatography , computer science , programming language
Integrated intensities of Bragg reflections have been measured at room temperature for Ni 3 Al alloys containing various amounts of boron, hafnium, zirconium and titanium and the data have been used to evaluate the mean Debye–Waller factors (〈B〉), Debye temperatures ( Θ M ) and long‐range‐order parameters ( S ). The Debye temperatures are observed to show a slight decrease with the decrease of aluminium content within the Ni 3 Al phase. The results for the Debye–Waller factors indicate that additions of the ternary elements hafnium, zirconium and titanium cause the mean Debye–Waller factor to increase linearly, while boron addition results in a nonlinear increase. The long‐range‐order parameter of stoichiometric Ni 3 Al is 0.97, which decreases with decreasing aluminium concentration from the stoichiometric composition. The long‐range‐order parameter of Ni 3 Al increases until 0.75 at.% B has been added, beyond that it remains constant. The long‐range‐order parameter of Ni 3 Al increases initially with the addition of hafnium, zirconium and titanium up to 0.50 at.% Hf and 0.52 at.%Zr, with further addition of hafnium and zirconium, it decreases. The results are discussed in relation to the crystal structure and chemical bonding in Ni 3 Al.