Accession Number : AD0605036

Title :   AMPLITUDES OF THERMAL VIBRATION AT FUSION,

Corporate Author : RAND CORP SANTA MONICA CALIF

Personal Author(s) : Gilvarry,J. J.

Report Date : 01 MAY 1956

Pagination or Media Count : 16

Abstract : On the basis of theoretical results from the Debye-Waller theory of the thermal dependence of x-ray reflection intensity, relatively accurate values of the Lindemann constant are determined for ten metals by use of rigidity moduli at fusion with previously determined bulk moduli. Agreement of the derived value, RHO, of the critical ratio of rootmean-square amplitude of thermal vibration to nearestneighbor distance at fusion, with the corresponding value from x-ray intensity data, is improved for the case (Al) favorable for comparison. The average value of RHO over the body-centered cubic, face-centered cubic, and hexagonal lattice types is 0-11 sub 1 in excellent agreement with the value 0.10 sub 5 given by Gruneisen. Relatively accurate values of the Lindemann constant for Pb and Al imply that this quantity can not be a strict constant over a lattice type; however, the assumption of an average over the lattice type yields an excellent approximation for the face-centered cubic elements. (Author)

Descriptors :   (*CRYSTAL LATTICES, VIBRATION), METALS, MELTING, THERMODYNAMICS, X RAY DIFFRACTION, CRYSTAL STRUCTURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE