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The molecular stability of metals, particularly of iron and steel

Nature
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https://doi.org/10.1038/041369e0

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Abstract

(1) ALLOW me to add some words relative to the very timely lecture on the hardening and tempering of steel, recently published by Prof. Roberts-Austen (NATURE, xli. pp. 11, 42). I desire, in the first place, to point out the bearing of the singular minimum of the viscosity of hot iron (loc. cit., p. 34) on the interpretation given of Maxwell's theory of viscosity (Phil. Mag. (5), xxvi. pp. 183, 397, 1888; xxvii. p. 155, 1889). When iron passes through Barrett's temperature of recalescence, its molecular condition is for an instant almost chaotic. This has now been abundantly proved (cf. John Hopkinson, Phil. Trans., London, clxxx. p. 443, 1889, where the literature may be found; cf. Osmond, below). The number of unstable configurations, or, more clearly, the number of configurations made unstable because they are built up of disintegrating molecules, is therefore at a maximum. It follows that the viscosity of the metal must pass through a minimum. Physically considered, the case is entirely analogous to that of a glass-hard steel rod suddenly exposed to 300°. If all the molecules passed from Osmond's β state to his a state together, the iron or steel would necessarily be liquid. This extreme possibility is, however, at variance with the well-known principles of chemical kinetics. The ratio of stable to unstable configurations cannot at any instant be zero. Hence the minimum viscosity in question, however relatively low, may yet be large in value as compared with the liquid state.

Publication type Article
Publication Subtype Journal Article
Title The molecular stability of metals, particularly of iron and steel
Series title Nature
DOI 10.1038/041369e0
Volume 41
Issue 1060
Year Published 1890
Language English
Description 3 p.
First page 369
Last page 371
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