COMPRESSION BEHAVIOR OF TIB2-PARTICULATE-REINFORCED COMPOSITES OF AL22FE3TI8

The compression behavior of both the monolithic L1(2) compound Al22Fe3Ti8 and discontinuous composites obtained by incorporating approximately 1-mu-m TiB2 particles was studied for various volume percent reinforcements as a function of temperature and at high temperatures as a function of strain rate. In this study, by varying the Fe and Ti contents, the nature and volume fraction of the minor phases coexisting with the dominant L1(2) phase were changed and were examined with and without TiB2 reinforcement. At high strain rates (10(-4) s-1), the TiB2 reinforcements significantly enhance ambient and warm-temperature strength, although a crossover is observed at approximately 1000 K, above which the monolithic material is stronger than the composite. At slow strain rates (10(-7) s-1), representative of creep conditions, however, the TiB2-containing composites retain their superiority at least up to 1200 K. Power law fits of compressive flow stress at 1% strain versus strain rate yielded a stress exponent of approximately 3.0 with an activation energy of 310 kJ/mol for the monolithic material. For the particulate composites (20 vol. % TiB2), the corresponding values were approximately 5.0 and 465 kJ/mol, suggesting a change in the dominant deformation mechanism.