The thermal expansion behavior of boron fiber-reinforced aluminum matrix composite subjected to thermal-mechanical cycling (TMC) was studied. Experimental results showed that TMC affected greatly the thermal expansion behavior of the composite. Using a simple analysis model of internal stress in the fibers, the stress change during the thermal expansion coefficient measurements of the composite subjected to TMC was calculated. The results indicated that TMC could induce the interfacial degradation of the composite, and the more the numbers of TMC cycles, or the higher the applied stress level of TMC, the more serious the interfacial degradation of the composite became. The proposed one-dimensional analysis model was proved to be a simple and qualitative approach to probing the interfacial degradation of unidirectional fiber-reinforced metal matrix composites during TMC. (C) 2004 Elsevier B.V. All rights reserved.