Simultaneous Multitemperature Measurements of Thermal Diffusivity and Composition

Abstract

It has been well established that thermal forcing of disordered multielement metallic alloys results in permanent modification of their thermal transport properties. The mechanism depends on the detail of heating and its duration, and entails rearrangement of the spatial distribution of constituent atoms within the material proper. It presents a serious complication in developing a body of properties data as a function of temperature because establishment of a thermal state for a specimen is often cast into question. A new general technique is presented for simultaneous multiple-temperature measurements of thermal diffusivity and local composition for a single specimen. The specimen is heated steeply into a state of temperature nonuniformity. The measurement is carried out by time-resolved spectroscopy of single-shot laser-produced plasma (LPP) plume emissions; analysis is made of the emissions as a function of position within the laser focal area. The procedure for analysis is presented together with the results for 80 mass% Ni-20 mass% Cr Nichrome specimens.