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ISSN: 0090-3973
Published Online: 1 May 1983
Page Count: 2

Short-Range Ordering in Nickel-Chromium Thermocouple Alloys
Pollock DD

Abstract
A short-range, lattice-ordering mechanism has been used extensively to explain the anomalous thermoelectric properties of such alloys as ChromelŽ and NicrosilŽ. This concept appears to have had its origin in early crystallographic work that postulated this mechanism to explain experimentally observed changes in the relative electrical resistance of nickel-chromium alloys. Later crystallographic work, confirmed by several additional investigators, shows no evidence for the existence of short-range order in nickel-chromium alloys containing less than 25 At % Cr. Other investigators, reviewing the short-term thermoelectric deviations of these alloys, describe this mechanism as much circumstantial evidence of a hypothesis that the short-term emf changes are due to short-range ordering in the Ni-Cr atomic structure of the Type KP thermoelement. Since short-range ordering has not been established as being responsible for the thermoelectric properties of nickel-chromium alloys, this mechanism may not arbitrarily be considered as the sole rationale for their behaviors.

Keywords:
nickel-chromium alloys, clustering, thermocouples, ChromelŽ, NicrosilŽ, short-range ordering, thermoelectric instability

Paper ID: JTE10684J
DOI: 10.1520/JTE10684J
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