THERMAL-EXPANSION BEHAVIOR AND MACROSTRAIN OF AL2O3 AL COMPOSITES WITH INTERPENETRATING NETWORKS/

The aim of the study is to investigate the thermal expansion behavior and internal residual strains in metal reinforced ceramic matrix compo sites (CMCs). A variety of Al2O3/Al CMCs with an interpenetrating netw ork structure were produced using a pressure infiltration technique. T he samples contained two variations in the average ligament diameter o f the metal phase of 0.15 mu m and 1 mu m and metal contents ranging f rom 13 to 40 vol.%. Coefficients of thermal expansion (CTEs) were foun d to vary significantly with temperature. It is proposed that this ind icates an influence of the flow characteristics of the metal. Comparis ons are made with well known methods for predicting CTEs of metal/cera mic composites. Overall strain increases with temperature scaled propo rtionally with metal content. Comparisons were made with uninfiltrated porous ceramic preforms and a pure metal sample. Hysteresis was obser ved between the heating and cooling of the composite samples at consta nt rate. (C) 1998 Acta Metallurgica Inc.