High-Temperature X-ray Diffraction Studies of Lattice Dynamics in Ni3(Fe,Nb) Ordered Alloys
A.O. Mekhrabov
Department of Metallurgical Engineering, Middle East Technical University, 06531 Ankara, Turkey
Received: August 3, 1993; in final form: November 16, 1993
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A study is performed on characteristics of lattice dynamics in the initially ordered ternary Ni3(Fe1-xNbx) (x = O to 10 at.%) alloys using high temperature X-ray diffractometry for the temperature range from 300 K to 1300 K. Aspects investigated included temperature and concentration dependencies of the full mean square atomic displacements Ū²f, the Debye characteristic temperature ΘD, and linear thermal expansion coefficient α. It is found that the Ū²f, ΘD, and α parameters show anomalous change at temperatures where the alloys are subjected to order-disorder phase transitions. It is further found that Nb addition results in the considerable increase in the parameters Ū²f and α and decrease in ΘD. Moreover, the addition of Nb stabilizes Ni3Fe ordered structure and shifts the order-disorder transition to higher temperature.
DOI: 10.12693/APhysPolA.85.571
PACS numbers: 61.10.-i