Intermetallic Matrix Composites via in-situ Displacement Reactions

摘要

Among the obstacles encountered in the development of intermetallic matrixcomposites are (1) the thermodynamic and mechanical incompatibility between the matrix and reinforcement phases and (2) the matrix reinforcement interfacial properties which are not ideal from the standpoint of achieving optimum properties in the composite as a whole. In the past, the first of these problems has been addressed by coating the reinforcements with some sort of barrier or compliant layer before their introduction into the matrix. The various coating methods investigated (sol-gel, CVD, PVD) tend to be expensive, time consuming and unreliable with respect to producing sound coatings. This research program was initially concentrated on identifying more cost effective and reliable schemes for developing the requisite coatings. The basic approach is to identify simple processing schemes whereby a beneficial reaction product (or products) is produced in-situ at the interfaces between the matrix and reinforcement during consolidation or subsequent heat treatment. As the research evolved, greater focus was placed on the need to achieve a better understanding of microstructural evolution during in-situ displacement reactions and on the correlation between the evolved microstructures and the mechanical properties.