Depth profile reconstruction of the thermal conductivity of inhomogeneous solids: application to laser-hardened Al alloys

Photoacoustic measurement techniques can be used to determine thermal prope rties on and below the sample's surface, thus subsurface thermal inhomogene ities, such as continuous profiles of thermal parameters, become measurable by photoacoustic methods. In this paper, the study is focused on the quant itative characterization of material modifications in subsurface layers of laser-hardened Al alloy samples. The variation of surface temperature is me asured by PA technique. Then a new numerical algorithm, carried out by empl oying the pulsed spectrum technique and the regularization method, is used to reconstruct thermal conductivity depth profiles, The experiment results demonstrate that the experiment and the algorithm are very effective for mi crostructure depth profile reconstruction by nondestructive method.