Developing multiphase Al3Ti alloys

To explore the approaches of combined toughening and strengthening of the Al3Ti-based LI2 intermetallic alloys, multiphase Al3Ti alloys formed by combining with reinforcement or by second phase precipitation are being studied. The interface reactions between Al66Fe9Ti25 matrix and SiC reinforcement were investigated. It is determined that SiC is chemically incompatible with the Al66Fe9Ti25 matrix, Al2O3 barrier coating on SiC by sol-gel process was developed to minimize the interfacial reactions. On the other hand, a new type of Al3Ti-based alloy having a LI2 matrix with second phase precipitation has been developed. The quaternary alloys based on Al67Mn8Ti25, and modified with Nb additions, consist of a LI2 matrix and DO22 second phase in the annealed state, but the second phase can be dissolved by solution treatment and precipitated during high temperature aging.