A quantitative study of vacancy defects in quenched platinum by field ion microscopy and electrical resistivity-II. Analysis and interpretation

A. S. Berger*, D. N. Seidman, R. W. Balluffi

*Corresponding author for this work

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

In the previous paper (Part I) it was demonstrated by means of field ion microscopy that the measured ratio of divacancy concentration to monovacancy concentration ( c2v c1v) in high purity platinum specimens quenched from 1700 ± 1°C was 0.06 ± 0.02. In the present paper (Part II), a detailed series of quantitative calculations was first performed which showed that this ratio was not affected by specimen storage and electropolishing procedures subsequent to the quench and hence represented c2v c1v at the "freeze-out" temperature (T*). It was then shown that all combinations of the divacancy binding energy (E2vb) and binding entropy (S2vb) which lead to a quenched-in value of c2v c1v equal to 0.06 ± 0.02 for a quench temperature of 1700°C are governed by the linear relationship E2vb = [(0.23 ± 0.03) + 6.17 · 10-2( S2vb k)]eV, where k is Boltzmann's constant. This linear equation implies that the divacancy binding free energy (G2vb) was 0.23 eV at T* = 443.4°C. This value of G2vb, calculated from our experimental data, depends only on a knowledge of the monovacaney migration energy and an approximate value of a frequency factor. The existing tracer diffusion data for platinum were re-examined in terms of a monovacancy and divacancy model in an attempt to decompose G2vb into E2vb and S2vb terms, and it was concluded that the available data are not sufficiently accurate to make this decomposition significant.

Original languageEnglish (US)
Pages (from-to)137-147
Number of pages11
JournalActa Metallurgica
Volume21
Issue number2
DOIs
StatePublished - Feb 1973

ASJC Scopus subject areas

  • Engineering(all)

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