This paper described a study of the thermal expansion behavior in a new aluminum matrix composite containing both beta-eucryptite particles and aluminum borate whiskers. The results of the measurements of the coefficient of thermal expansion (CTE) showed that the composite had both low thermal expansion coefficient and stringent dimensional stability at a wide temperature range. A simplified model was established and used to analyze the relation between thermal expansion behavior of the composite and thermal mismatch stresses in the whiskers and particles in the composite. Furthermore, the effect of interfacial reaction on the physical CTE of the composite was investigated with the help of transmission electronic microscopy (TEM). (C) 2004 Elsevier B.V. All rights reserved.