Some Studies on Recovery & Oxidation Characteristics of Copper by Thermoelectric Phenomenon

Abstract

It is well known that the junction of two dissimilar metals is the seat of thermoelectric force which can be used for the measurement of temperature.For this purpose usually dissimilar metals and/or alloys are used . In such cases the metals or alloys invariably differ in chemical composition.Although some work has been done to investigate the changes in the thermoelectric properties of the same metal or alloy due to some physical changes ( without any change in chemical composition ),not much of work has been , done to study minute changes occurring in metals and alloys which do not appreciably affect either the microstructure or the mechanical properties. For example, neither the microstructure nor such mechanical properties as hardness, tensile strength and ductility undergo any appreciable change during the so-called ' recovery stages' of cold-worked metals and alloys or the so-called ' pre -precipitation stages'during ageing, tempering and other thermal treatments of metals and alloys.An attempt has been made in this investigation to show that changes in the thermoelectric properties of metals and alloys may well be taken advantage of to detect minute changes in metals and alloys -be it on the surface or inside the volume. In a pure specimen of copper wire it has been shown that (i) there are detectable and continuous changes in the thermoelectric properties throughout the recovery stage of the cold-worked specimen,and (ii) there are very sharp discontinuities in the e.m.f. temperature plot in the initial stages of film formation during heating in air. Further work is in progress to detect the changes in the initial stages of ageing, tempering and other transformations -isothermal or otherwise-in other metals and alloys.