41^e Colloque de Métallurgie de l'INSTN
Ségrégation interfaciale dans les solides

J. Phys. IV France 09 (1999) Pr4-201-Pr4-206
DOI: 10.1051/jp4:1999426

Résistance thermique d'interface aux joints de grains dans le nitrure d'aluminium polycristallin

C. Pélissonnier-Grosjean¹, D. Fournier² and A. Thorel<sup>3

1</sup>  MATOP, UA CNRS, Case 151, Faculté des Sciences et Techniques de Saint Jérôme, 13397 Marseille cedex 20, France
²  Laboratoire d'Instrumentation de l'Université Pierre et Marie Curie, École Supérieure de Physique et Chimie Industrielle de Paris, 10 rue Vauquelin, 75231 Paris cedex 05, France
³  École Nationale Supérieure des Mines de Paris, Centre des Matériaux P.M. Fourt, BP. 87, 91003 Évry cedex, France

Abstract
Polycristalline aluminium nitride exhibit poor thermal conductivity in comparison with that of monocristalline nitride. This is due to microstructural features specific of ceramic materials such as impurities, secondary phases or grain boundaries... In an attempt to understand the effect of grain boundaries on the macroscopic conductivity of yttria doped polycristalline aluminium nitride, local thermal measurements were achieved on two materials of quite different microstructure. Thermal investigation was performed by means of photoreflectance microscopy, a photothermal variant which allows a spatial resolution of a few micrometers. The experimental results are discussed in terms of thermal discontinuities or thick interphases of poor thermal properties at the boundaries. They are also linked to grain boundaries microstructural features. Moreover, the induced effect of each thermal behaviour on the macroscopic conductivity evaluation is presented.

© EDP Sciences 1999