Book Description

Nearly 70 years ago, the first dispersion -strengthened alloy was marketed commercially. This material, thoriated tungsten, has been of considerable industrial importance since then and new uses for the alloy are still being found. Much later, in the early 1950's, the marketing of sintered aluminum products (SAP)was started with great expectations that never materialized. This development, however, encouraged research and development in applying dispersion hardening to many metals and alloys, a number of which have been offered to industry. The main reason for interest is that these materials have markedly improved creep resistance over the original base metal and that this strength advantage can be maintained at very high temperatures, e.g., frequently up to 90 percent of the base metals' homologous melting temperature (0.9 Tm).Unfortunately, most of the dispersion -strengthened materials that have been marketed could not compete pricewise with other materials available. Joining problems have also inhibited their wider use. However, as the pressure for increasing service temperatures becomes greater, particularly in thermal shields and aircraft gas -turbine engines, the prospects of using dispersion -strengthened alloys to meet these needs becomes brighter. This would not be true without several important processing developments that have occurred within the past 10 years. These include mechanical alloying, directional recrystallization, and new concepts in thermomechanical processing. The net result should be a promising future for the most advanced of the dispersion -strengthened (DS) alloys. It is also probable that new uses will continue to be found for the important established, though less glamorous, DS alloys of tungsten, silver, and copper. This review consists of a brief assessment of the developments in dispersion strengthening of 21 metals and their alloys, with a special emphasis on the last 10 years.